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roasted garlic mashed potato casserole
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Roasted Garlic Mashed Potato Casserole

Creamy mashed potato, flavoured with roasted garlic & topped with cheese, bacon & breadcrumbs then baked until crisp. This is an indulgent side dish that's perfect for Thanksgiving.
Prep Time30 minutes
Cook Time1 hour 30 minutes
Total Time2 hours
Course: Side Dish
Cuisine: American
Servings: 8 People
Author: Ben Racey

Equipment

  • Large Baking Tray
  • Potato Ricer
  • Mixing Bowl
  • 10" Round Baking Dish (Or A Similar Size Square/Rectangle One)
  • Cheese Grater

Ingredients

Baked Potatoes & Garlic

  • 2.5 kg Maris Piper Potatoes (See Notes)
  • 1 Garlic Bulb
  • 2 tsp Vegetable Oil

Infused Cream

  • 250 g Double Cream
  • 200 g Whole Milk
  • A Few Sprigs Of Rosemary
  • A Few Sprigs Of Thyme
  • Nutmeg (To Taste)

Mashed Potato Casserole

  • 250 g Sour Cream
  • 100 g Mature Cheddar
  • 100 g Red Leicester
  • 40 g Panko Breadcrumbs
  • 6 Rashers Of Streaky Bacon (Smoked Or Unsmoked)
  • Finely Chopped Chives (To Serve)

Instructions

Roasted Potatoes & Garlic

  • Preheat an oven to 200°c/180°c fan (392°f/356°f).
  • Prick the potatoes all over with a fork then place onto a large baking tray.
  • Next, cut a small amount off the top of the garlic bulb, to expose the garlic inside then place onto a piece of foil, drizzle over the veg oil then wrap up in the foil.
  • Place the foil wrapped garlic onto the tray of potatoes then place into the preheated oven. Bake until the potatoes are tender & the garlic is soft. This will take around 1 hour.
    Give the potatoes a poke with a small knife. If it slides into the potato with little to no resistance, they're cooked. The garlic will take 45 minutes - 1 hour to cook so might be done before the potatoes.
  • Once cooked, let the potatoes & garlic cool for 15-20 minutes before mashing. The potatoes need to be warm when we mash them but not too hot, as they'll be difficult to handle.
    We'll be baking the casserole at the same oven temperature so you can leave it turned on or preheat it again if you're not baking it straight away!

Crispy Bacon

  • Whist your potatoes are cooking, fry the streaky bacon until golden & crispy. You can do this in a frying pan over a medium heat or under a grill. It's up to you!
  • Once cooked, let the bacon drain on a plate lined with kitchen paper.

Infused Cream

  • Whilst your potatoes are cooling, place the cream, milk, herbs & nutmeg into a saucepan, season well with salt & pepper then warm over a low heat until steaming hot. Set to one side & leave to infuse until you mash the potatoes.

Mashed Potatoes

  • Grate both of the cheeses, place into a mixing bowl & mix to combine. Set aside for now.
  • Next, cut the potatoes in half then use a spoon to scoop out the flesh. Use a potato ricer to mash the potatoes into a large mixing bowl.
    If you haven't got a ricer, scoop the potato out of the skins, place into a mixing bowl then use a potato masher to mash once you've added in the cream & milk.
  • Squeeze the roasted garlic cloves out of their skins then use the potato ricer to mash into the potatoes.
  • Pour the infused cream into the potatoes through a sieve then add in the sour cream & half of the grated cheese. Mix to combine then season to taste with more salt & pepper as needed.
  • Transfer the mashed potatoes into a large baking dish that has been lightly greased with butter, spreading it out into an even layer. I like to place the dish onto a baking tray, as this makes it easier to take out of the oven!
    I used a 10" round baking dish.
  • Next, chop the crispy bacon into small, bitesize pieces, place into a small mixing bowl with the breadcrumbs then mix to combine.
  • Sprinkle the bacon & breadcrumbs over the top of the mashed potatoes then sprinkle over the rest of the grated cheese. Bake in the preheated oven for 20-25 minutes until the top is crisp & golden and the mash is piping hot.
  • Once cooked, top the casserole with a sprinkle of finely chopped chives then serve!

Notes

 1. To Cook In An Aga - Bake the potatoes & garlic in the roasting oven, on the bottom set of runners & use the simmering plate to warm the cream. The mashed potato casserole can be baked on the bottom set of runners in the roasting oven or on the second from top set of runners in the baking oven.
2. Potatoes - A floury variety of potato is best for mashing. I used Maris Pipers but Russets or King Edwards will work as well. We're baking our potatoes instead of boiling them as they'll have more flavour & will make a fluffier mash.
3. Dairy - For a super creamy mashed potato, we're using a mix of double cream, milk & sour cream. I've not added any butter to the mash as there's plenty of dairy in there already but feel free to add some in if you like. 
4. Cheese - I used a mix of mature cheddar & red Leicester but feel free to use pretty much whatever cheese you like! Some good alternatives would be parmesan, Gruyere or Monterey Jack. You could use cream cheese instead of sour cream as well, if you'd prefer a less tangy flavour.
5. Making In Advance - Mashed potato casserole is a great side dish to make ahead of time. To do this, make the mashed potato & place into a baking dish then leave to cool, cover in clingfilm then store in the fridge for up to 3 days. When you're ready to bake the casserole, let it sit out of the fridge for an hour. In the meantime, cook the bacon breadcrumbs then top the casserole with the cheese & bacon and bake following the instructions in the recipe.