Make-ahead Mashed Potato Casserole

January 7, 2023  Chef Austin Avatar
Make-ahead Mashed Potato Casserole

Scooping up Mashed Potato Casserole

Mashed Potato Casserole is an outrageously delicious yet highly practical way to make mashed potato ahead of time! A layer of cheese and bacon prevents the mash from drying out as it reheats in the oven, while transforming this humble side into something extra-devilish and decadent. Oh the power of cheese (plus bacon)!

Make it fresh, or assemble ahead and reheat when required. Serve in place of plain ole’ mash.

Scooping up Mashed Potato Casserole

Make-ahead mashed potato

With the holidays fast approaching, I thought it would be timely to share my favourite way to make mashed potato ahead of time.

The thing with make-ahead mash is that you cannot simply reheat it in the microwave or oven. You might think a splash of milk and good stir is all it takes to restore it. But I can tell you that’s the path to a mouthful of gluey horridness.

While there are nifty ways to reheat cold mashed potato successfully*, a big dish of creamy Mashed Potato Casserole takes the prize for the most foolproof-yet-show-stopping way I know! It also wins the prize for the lowest effort on the day-of because you literally just pop the pre-assembled dish into the oven. It’s a win-win, 10/10 – nothing could be more fitting for your holiday feast menu!!

* How I reheat plain mashed potato: Cold mash in hot cream (recipe here, but note it’s more work on the day) or in heavy duty piping bags submerged in boiling water, a trick caterers use (see my demo here on Instagram).

Close up of Mashed Potato Casserole

Is there such a thing as too much bacon??

Confession: I think I was a little heavy-handed with the bacon in the photos while being a tad short on the stuff for the recipe video!! So the recipe card as written is a happy medium. 😊

But actually, looking at the photo below, it does look pretty enticing with almost full bacon coverage on the surface. And … is there even such a thing as too much bacon?? (Yeah nah)

Freshly made Mashed Potato Casserole

What you need for Mashed Potato Casserole

Here’s what you need to make Mashed Potato Casserole:

Ingredients in Mashed Potato Casserole
  • Potato – Floury and all-rounder potatoes work best to achieve a fluffy yet creamy mash without fussing with potato ricers and other gadgets.
    – Australia: the cheap dirt-brushed potatoes sold everywhere (called Sebago) are ideal
    – US: Russet
    – UK: Maris Piper

  • Milk – Our liquid to loosen the potato up to form mash. If making ahead, we add extra (see How To Make section for more).

  • Sour cream – I prefer using sour cream rather than cream in mashed potato casserole because the slight tang makes a nice counterpoint to all the other richness going on here (butter, cheese, bacon). It doesn’t make it sour in the least. It sort of adds creaminess into the mash without adding cloying richness. Does that makes sense??

  • Butter – Mash without butter is not mash. #strongopinions!

  • Cheese – I use a combination: Mozzarella for excellent melty-cheesy-stretchines. Then Red Leicester for flavour (it’s savoury and a bit sharp, like aged cheddar), and to add a lovely orange hue to the mash surface. If you’re in the States, your orange cheddar is ideal here.

    Otherwise, use any melting cheese you like (colby and Monterey Jack are other personal favourites). If you opt to use mozzarella as your main cheese, add a handful of parmesan for flavour because mozzarella alone is actually quite bland and lacks saltiness.
    Shred your own – One of my five non-negotiable rules stated loudly on the first page of my cookbook is, “Always shred your own cheese”! Store-bought pre-shredded cheese is coated in anti-caking agents which prevent it from melting as well as freshly-grated. I use a standard box grater for the work.
    Pack your cups of cheese – For consistency I prefer weight over volume to measure cheese. So I’ll weigh a hunk of cheese before grating it. But if you are using cup measures, be sure to pack your cups tightly when measuring the shredded cheese otherwise you will be short. Nobody wants to be short on cheese, ever!

  • Bacon – For sprinkling over the casserole surface. Note: I always use streaky bacon. Because fat = flavour! Also, fatty bacon crisps up and colours better, without drying out.

  • Green onion – For a touch of oniony freshness and colour.

How to make Mashed Potato Casserole

No rocket science here. We make mash, spread it into a casserole dish, top with cheese, bacon and then stop here if making ahead. Finally, on the day of your do, bake it!

How to make Mashed Potato Casserole
  1. Cut potatoes – Peel and cut the potatoes into even sized pieces.

  2. Boil until soft – Place the potatoes in cold salted water, then bring it up to a boil and cook until soft. They should fall apart when you jab it with a fork. This will take 12 to 15 minutes depending on how strong your stove is and the efficiency of your pot.

  3. Mash – Drain the potatoes well in a colander and pour them back into the empty pot. Mash with the butter, milk, sour cream and salt.

    MAKE-AHEAD ADJUSTMENT – If you are making this dish with the intention of serving it the next day, then add an extra 2/3 cup milk. The mash will seem too loose, but this is intentional. It is to factor in the fact that mashed potato firms up when refrigerated overnight. So once reheated, it has the same consistency as when it is freshly made!

    Potato masher – I like to use a potato masher that is like a round disc with holes in it, as pictured above. It’s the fastest and most effective tool for a smooth mash without using a potato ricer (which I reserve just for Paris Mash, when seeking that next-level-luxe, ultra-smooth, 3-Michelin-restaurant result!).

  4. Spread in a casserole dish.

How to make Mashed Potato Casserole
  1. Top with the cheeses and bacon. (Yes you eagle-eyed spotters, I was short on bacon for these shots 😂)
    For make ahead – At this stage, the assembled dish can be popped in the fridge for up to 3 days. Just take it out of the fridge 2 hours ahead so it has time to de-chill. This will make it reheat faster and more evenly in the oven.

  2. Cover with foil then bake for 20 minutes at 200°C / 400°F (180°C fan), if freshly made. Add an extra 15 minutes if you’re reheating a make-ahead casserole you prepared the day before.

  3. Uncover – Remove from the oven and bake for a further 10 minutes until bubbly and golden.

  4. Voila, ready to serve! Crack through that molten cheese surface and marvel at how creamy the mash underneath is!

Big pan of Mashed Potato Casserole

Bowl of Mashed Potato Casserole

How to serve Mashed Potato Casserole

This is a dish designed to be a side. (I know we can all picture it moonlighting as a standalone dish after a big night on the turps or a shocking day at work, but it’s meant to take the place of traditional plain mashed potato, I swear.) Because actually, though this has cheese and bacon on it, underneath is all creamy plain mashed potato.

So place it on the table or on the buffet alongside the mains and let everybody dig in and help themselves! Try to get in first though. Because you know full well the first in line are going to take more than their fair share of that cheese bacon topping – and we know full well we also cannot blame them….. – Nagi x

Watch how to make it

Scooping up Mashed Potato Casserole


Mashed Potato Casserole

Recipe video. This is an outrageously delicious yet highly practical way to make mashed potato ahead of time! A layer of cheese and bacon prevents the mash from drying out as it reheats in the oven, while transforming this humble side into something extra-devilish and decadent. Oh the power of cheese (plus bacon)!

Make it fresh, or assemble ahead and reheat when required. Serve in place of plain ole' mash.

Course Potatoes, Side Dish
Cuisine Western
Keyword mashed potato bake, mashed potato casserole
Servings 10 – 12
Calories 333cal
Author Nagi


  • 1.75kg/ 3.5 lb potatoes (Sebago (Aus), Russet (US), Maris Piper / King Edwards (UK)(Note 1)
  • 1 tbsp cooking / kosher salt , for cooking potatoes
  • 2/3 cup milk (preferably full fat/whole milk but lite ok)
  • 2/3 cup EXTRA milk , for make-ahead option only (Note 2)
  • 75g / 5 tbsp unsalted butter , cut into 1cm / 1/2″ cubes
  • 1/2 cup sour cream (or yogurt), full fat best
  • 1 1/2 cups (tightly packed) mozzarella , freshly shredded (Note 3)
  • 1 cup (tightly packed) Red Leicester, cheddar or other flavoured cheese(Note 3)
  • 1 tsp cooking/kosher salt , or to taste
  • 200g / 6 oz bacon (streaky), chopped (Note 4)
  • 1/4 cup green onion , finely sliced


Cook bacon:

  • Place bacon in a cold non-stick pan over medium heat (no oil). As the pan heats up the bacon fat will melt. Once you see some melted bacon fat, turn the heat up to medium high and stir for 3 minute or until golden.
  • Drain on paper towels.


  • Potatoes – Peel then cut into 3cm /1" chunks.
  • Boil – Place in a large pot and cover with water so it’s 10cm / 4” above the potatoes. Add 1 tablespoon salt. Bring to a boil over high heat then reduce heat so it’s simmering rapidly. Cook 15 minutes or until potatoes are very soft (jab with fork to test, they should fall apart).
  • Drain well, then return into pot. Leave for 1 minute, shaking pot every now and then, to encourage evaporation of water.
  • Mash – Add milk (including EXTRA milk if making-ahead), butter, sour cream and 1 tsp salt. Mash until smooth. (Do not use food processor, blender or beater, makes it gluey!)

Make-ahead directions:

  • Fridge – Allow to fully cool on the counter then cover tightly with cling wrap and refrigerate.
  • Dechill – Take out onto counter 2 hours prior to reheating.


  • Spread the potato in a 2 litre / 2 quart baking dish (Note 5). Smooth the surface.
  • Sprinkle – Sprinkle potato with the cheeses, then bacon.
  • Bake covered – Cover loosely with foil. Bake 20 minutes covered (if freshly made) or 35 minutes (make-ahead option).
  • Bake uncovered – Remove foil then bake a further 10 minutes until the cheese is bubbly and golden.
  • Serve – Sprinkle with green onion then serve! It stays warm for a good 20 minutes thanks to that protective layer of cheese. Oh, the powers of cheese!


1. Potatoes – Any starchy or all-rounder potatoes suitable for making mash will work great.

2. Extra milk for make-ahead option makes the mash looser to factor in that mash firms up when refrigerated. This is the amount required so that the reheated dish ends up with the same consistency as when it was freshly made!

3. Cheeses – Mozzarella for excellent melting qualities, plus Red Leicester or US cheddar for colour and flavour (sub with other cheese of choice like colby, gruyere, Swiss, tasty).

SHRED YOUR OWN for the best result! Store-bought pre-shredded is coated with anti-caking agents so it doesn’t melt as well.

PACK your cups tightly when measuring shredded cheese, else you’ll be short. And nobody wants to be short on cheese, ever!

4. Bacon – You need to use streaky/fatty bacon to use this no-oil method of cooking bacon. If you use lean bacon, you will need to preheat oil. I know which option I prefer! 🙂

5. Dish – A 2 litre / 2 quart baking dish is the ideal size, it will be filled to the brim. A 23 x 33cm / 9 x 13″ dish (3L/3 qt) works fine too – will be filled about 2/3 of the way up.

6. Make-head – Keeps for 3 days in the fridge, uncooked, fully assembled except for the green onion. Be sure to take it out of the fridge 2 hours prior to reheating to take the chill out of the it so it reheats more evenly.

Freezing – A former team member reported excellent results freezing the assembled dish, thawing then reheating. But I never tried it myself – I will come back and update if (no, when!) I do.

Leftovers will keep for 3 days, but the mash won’t be as creamy. Consider using it to make mashed potato cakes instead!

7. Nutrition per serving assuming 12 servings, as part of a larger banquet.


Calories: 333cal | Carbohydrates: 26g | Protein: 11g | Fat: 21g | Saturated Fat: 11g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 6g | Trans Fat: 0.2g | Cholesterol: 54mg | Sodium: 1057mg | Potassium: 668mg | Fiber: 3g | Sugar: 3g | Vitamin A: 478IU | Vitamin C: 27mg | Calcium: 200mg | Iron: 1mg

Life of Dozer

People have been wondering how Jeff is, our friendly local who lives at my local dog park (Bayview, in Sydney’s northern beaches), an official RecipeTin taste tester. He is doing well! This is how I start every weekend – coffee for Jeff, a ham and cheese croissant for his dog Cubby (sometimes Jeff gets a bite) and Dozer, waiting for scraps – until he gives up and gallops down to the beach to join his mates in the water!

Photo captured by Kevin of Unleashed Northern Beaches, a local photographer. Wonderful gift idea: voucher for a private pooch photo shoot!

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