Creamy, buttery, cheesy, bacon-y mashed potato, topped with caramelized onions plus MORE golden, bubbling, melted cheese and crispy bacon bits. It really is mashed potato heaven.
Even better – you can make this ahead (up to two days ahead) and easily reheat as a luxurious side dish. A great make-ahead dish for Thanksgiving or Christmas dinner!
Just when you thought mash couldn’t get any better, adding cheese, onions, and crispy, salty morsels of bacon brings it to a whole other level!
This is supposed to be a side dish that you can make ahead to bring to family dinner but I almost can’t resist eating this right out of the oven by the spoonful. 😆 This is bound to be a family favourite at the dinner table (my youngest will absolutely lick the dish clean if I let him).
Table of Contents
📋 Ingredients
Potatoes (floury rather than waxy potatoes) – Floury potato varieties include Maris Piper, King Edwards, Rooster, Russets, Yukon golds or Desirée.
Cheese – I used a mix of Cheddar and Red Leicester but you can use your favourite type of cheese.
How to make it:
***Full recipe with detailed steps in the recipe card at the end of this post***
- Peel and boil the potatoes until tender. While the potatoes are boiling, fry up the bacon and chop into bits.
- Mash the potatoes – I love using my potato ricer (<–affiliate link) for extra smooth mash. Stir in the butter, milk cream, salt and pepper, then the cheese and most of the bacon and spoon it all into a large baking dish.
- Fry the onions in the pan you cooked the bacon (bacon fat + onions = ❤️️) until soft and golden.
- Spoon the cooked onions on top of the mash and sprinkle over more cheese. Cook for 20 minutes covered with foil, then remove the foil sprinkle on the remaining bacon and cook for a final 10 minutes.
- Top with chopped spring onions (scallions) and serve.
Pro Tip
If you don’t want to make the mash from scratch, you can use frozen mash pellets. See the notes section for more info.
When it comes to adding bacon, measure with your heart!
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Pin It🍽️ What to serve it with
This is a brilliant side dish to bring along to your Christmas or Thanksgiving dinner:
🍲 More fantastic side dishes
? Frequently Asked Questions
Yes! See the bottom of the recipe card in the section entitled ‘If Making Ahead’ for specific instructions.
If you don’t want to peel, boil and mash the potatoes, frozen mashed potato pieces/pellets are a great alternative.
*However* you can only use this method if you’re cooking and serving right away. Frozen mashed potato pellets are already cooked, so it’s not a good idea (from a food safety point of view) to heat them up, make them into the mashed potato casserole, cool, chill and then reheat a third time.
If you want to use the frozen mashed potato pellets, I would use 1.8kg (4lbs) of frozen mashed potato. Heat the mashed potato as per the pack instructions in the microwave, then add the butter, cream, milk and seasoning and continue with the rest of the recipe. (see the notes section for more info)
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Make Ahead Mashed Potato Casserole with Bacon
Equipment
Ingredients
Mashed Potato:
- 1.5 kg (3.3lb) floury potatoes (see notes) – chopped into even-sized chunks (see notes)
- 80 g (1/3 cup) unsalted butter
- 80 ml (1/3 cup) double (heavy) cream
- 60 ml (1/4 cup) full fat milk
- ½ tsp table salt
- ½ tsp black pepper
- 75g g (3/4 packed cup) mixed grated (shredded) cheese I use Cheddar and red Leicester
Onion, bacon and cheese toppings:
- 1 tbsp oil
- 200 g (7 oz) rashers (strips) of smoked bacon
- 30 g (2 tbsp) unsalted butter
- 2 medium onions, peeled and thinly sliced
- ½ tsp salt
- ½ tsp black pepper
- 150 g (1+1/2 packed cup) mixed grated (shredded) cheese I use Cheddar and red Leicester
To Serve:
- 3 tbsp finely sliced spring onions (scallions)
Instructions
Boil the Potatoes:
- Place the potatoes in a pan and cover with cold water.1.5 kg (3.3lb) floury potatoes (see notes)
- Bring to the boil and simmer for 15-20 minutes. Check after 15 minutes by pushing a knife into one of the potatoes – the potato should be tender and the knife should slide through. Cook for a few minutes more if needed to get to the this stage, but don't let them overcook (no more than 20 minutes) or the mashed potatoes will be watery.
Bacon:
- While the potatoes are boiling, we're going to cook the bacon. Heat the oil in a large frying pan over a medium-high heat.
- Add the bacon in a single layer, to the pan (you may need to work in two batches if your pan isn't large enough). Fry for 6-7 minutes, turning once, until crisp.
- Remove the bacon from the pan with a set of tongs and place on a board. Chop the bacon into small pieces and put to one side. Don't wash the pan – we want that flavourful bacon grease!
Make the cheesy mashed potatoes:
- By now the potatoes should be ready. Drain the potatoes in a colander and let them sit for 1 minute, until the moisture evaporates.
- Place the potatoes – about 2 at a time – in a potato ricer, letting the riced potatoes fall into a clean bowl. Continue until all the potatoes are riced.
- Add the butter and give it a little stir so the heat of the potato melts the butter.80 g (1/3 cup) unsalted butter
- Add the cream, milk, salt, and pepper and stir together using a wooden spoon until smooth and creamy.80 ml (1/3 cup) double (heavy) cream, 1/2 tsp table salt, 1/2 tsp black pepper
- Stir in the cheese and three-quarters of the chopped bacon, then spoon the mashed potato mixture into a large baking dish (mine is approx 30cm(11.8")x22cm(8.66")and 5cm(2") deep. Note: If you're planning on making this dish ahead and reheating later, make sure your dish is no deeper than 5cm (2 inches). The mashed potato will take FOREVER to reheat if you're using a deeper dish.3 tbsp finely sliced spring onions (scallions)
Fry the onions:
- Add the butter to the frying pan with the bacon fat in. Heat over a medium heat until the butter melts.
- Add the onion to the pan and fry for 8-10 minutes, stirring often, until softened and slightly browned. Meanwhile, preheat the oven to 180C/375F (fan). See below if you're making this ahead and not serving this right away.
Assembly and Baking:
- Spoon the onions on top of the mashed potatoes. Sprinkle the cheese on top and cover with foil.
- Place in the oven for 20 minutes.
- Remove the foil and sprinkle the remaining bacon on top. Place back in the oven (uncovered) for 5-10 further minutes – until the mash is hot, the cheese is golden and the bacon has warmed through.
- Serve topped with spring onions (scallions).
If Making Ahead:
- Once you've added the onions and cheese on top of the mashed potatoes, leave the dish to cool, then cover with foil and place in the refrigerator (for up to two days). Put the remaining cooked bacon in an airtight container in the fridge too.
- Take the mashed potato out of the refrigerator about 2 hours before you want to cook it – this will allow it to come closer to room temperature, so the centre isn't cold.
- Preheat the oven to 180C/375F (fan).
- Place in the oven for 45 minutes – covered with foil.
- After 45 minutes, remove the foil and sprinkle the cooked bacon on top. Place back in the oven (uncovered) for 5-10 further minutes – until the mash is hot, the cheese is golden and the bacon has warmed through.
- Serve topped with spring onions (scallions).
Notes
Potato Variety
Potato varieties for floury potatoes include Maris Piper, King Edwards, Rooster, Russets, Yukon golds or Desirée.Chopping the potatoes
You want medium-sized chunks – about the size of half a kiwi fruit . The key is to ensure they’re cut into similar sizes, so they’ll cook evenly.Frozen mashed potato pellets option
If you don’t want to peel, boil and mash the potatoes, frozen mashed potato pieces/pellets are a great alternative.*However* you can only use this method if you’re cooking and serving right away. Frozen mashed potato pellets are already cooked, so it’s not a good idea (from a food safety point of view) to heat them up, make them into the mashed potato casserole, cool, chill and then reheat a third time. If you want to use the frozen mashed potato pellets, I would use 1.8kg (4lbs) of frozen mashed potato. Heat the mashed potato as per the pack instructions in the microwave, then add the butter, cream, milk and seasoning and continue with the rest of the recipe.
More info on frozen mashed potato pieces or pellets
They’re available in bags from the frozen aisle of the supermarket. I’ve bought it from Sainsburys and Ocado, but have also seen it in Tesco, Waitrose and Iceland.It’s been a game changer for me when making mashed potato recipes and I thoroughly recommend it.
I’ve found when looking at the ingredients, they usually contain potato and just a little milk and butter – no weird ingredients. It’s worth checking this too before you buy. Nutritional information is approximate, per serving, based on this recipe serving 8.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
Some of the links in this post may be affiliate links – which means if you buy the product I get a small commission (at no extra cost to you). If you do buy, then thank you! That’s what helps us to keep Kitchen Sanctuary running. The nutritional information provided is approximate and can vary depending on several factors. For more information please see our Terms & Conditions.
