Mashed Potatoes au Gratin.
I’ve never met a potato I didn’t like. This recipe is a classic but nothing like you’ve ever tasted before. Mashed Potatoes au Gratin combines the creamy, buttery, comfort of mashed potatoes with the golden cheesy crust of au gratin. In the words of Hannah Montana, you get the best of both worlds!
Why you'll love my recipe.
Creamy meets crispy
You get the smooth, buttery goodness of mashed potatoes topped with the crispy, golden cheesy potato layer of au gratin.
Simple prep
All you need are a few pantry staple ingredients. You can even prepare this dish in the morning.
Eye-catching presentation
Impress your company without all the effort. Perfect for the holidays, any special occasion or when you need a vegetarian side dish.
Ingredient notes.
Yukon gold potatoes
You may substitute for Idaho Russet Potatoes. We use potatoes two ways in this recipe. Mashed for the base and thinly sliced for the topping.
Heavy cream
Brings creaminess and depth that help with the classic mashed potato texture.
Butter
For a little extra flavor and richness.
Garlic
Garlic is infused into the heavy cream. Measure with your heart.
Gruyere and parmesan
Gruyere melts beautifully with a nutty, sweet taste. Parmesan is what adds a salty kick and crisps up nicely to create a bubbly, golden crust on top.
For the rest of the ingredients, please see the recipe index card below!
What should I serve Mashed Potatoes au Gratin with?
It pairs well with a variety of main courses. Think traditional Thanksgiving and Christmas spread with my Hot Honey Bacon Wrapped Carrots and Soft Dinner Rolls.
Why do I need to heat up the cream and butter?
Heating up the cream and butter before adding to mashed potatoes is key for achieving a smooth and creamy texture. Hot cream and butter blends easier with the warm potatoes, creating more fluff and evenly dispersed flavor throughout.
Can I make this dish ahead?
Yes! The night before, simply make the mashed potatoes, prepare it in an oven safe baking dish with the thin potato layer topping and cheese. Wrap the top in foil and store in the refrigerator. Then, simply bake with the foil on and proceed with the rest of the baking directions. That’s it!
How to make Mashed Potatoes au Gratin.
Preheat the oven
Set your oven to 400°F / 204°C.
Prepare the mashed potatoes
Wash, peel and cut potatoes into equal cubes. Boil for 20-25 minutes until fork tender. Strain the water and return back to the pot.
Make the cream sauce
Add the cream, butter and garlic to a small saucepan. Heat up over low heat until steaming. Combine the cream sauce with gruyere in the same pot as the potatoes. Use a hand mixer to beat until smooth and fluffy.
Assemble the layers
Spread the mashed potatoes in a medium size shallow, casserole dish. Top with a layer of thinly sliced potatoes, gruyere and cover with foil. If using a mandolin, be careful not to slice your fingers tips! Shop my exact mandolin here. (Affiliate link)
Bake
Bake for 25 minutes. Then, remove the foil and add parmesan on top. Bake for an additional 20 minutes or so until golden and bubbly. Broil the last 2-3 minutes for extra crisp.
Expert tips.
Choose the right potatoes
Yukon Gold or Russet potatoes work best due to their creaminess and ability to hold their shape. Yukon Gold has a naturally buttery flavor and texture.
Slice thinly and evenly
Use a mandolin for consistent, thin slices, about 1/8 inch thick.
How do I re-heat leftover mashed potatoes?
Mashed potatoes get dry when they cool because the starch molecules in the potatoes recrystallize and absorb moisture, causing once fluffy potatoes to become stiff and lose their fluffy texture. The butter and cream that keep them moist harden when cooled, thus contributing to the dryness.
To reheat mashed potatoes and bring them back to life, you must add moisture back! Reintroduce a liquid like half and half or broth (for a lighter option) before reheating. Reheat over medium-low heat in a small pot on the stovetop. Whisk frequently to prevent sticking and reintroduce air and fluff it up again.
How to store leftover mashed potatoes.
While you can store leftovers in the refrigerator if needed, the combination of crispy bacon and tender carrots are best served fresh out of the oven. The natural moisture from the carrots can make the bacon soggy over time.
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Mashed Potatoes au Gratin
Ingredients
For the mashed potatoes:
- 4 pounds Yukon gold potatoes, 10 medium size peeled and diced
- 1/2 cup heavy cream or half and half
- 1/2 cup unsalted butter
- 5 garlic cloves measure with your heart
- 1 teaspoon sea salt adjust to taste
- 1/2 heaping cup gruyere
- Thyme optional
For the topping:
- 4 Yukon gold potatoes, thinly sliced
- 1/2 heaping cup parmesan
- 1/2 heaping cup gruyere
Instructions
Preheat the oven.
- Set your oven to 400°F / 204°C.
Prepare the mashed potatoes.
- Wash, peel and cut potatoes into equal cubes. Boil for 20-25 minutes until fork tender. Strain the water and return back to the pot.4 pounds Yukon gold potatoes, 10 medium size
Make the cream sauce.
- Add the heavy cream, butter, salt and garlic to a small saucepan. Heat up over low heat until steaming.1/2 cup heavy cream or half and half, 1/2 cup unsalted butter, 5 garlic cloves, 1 teaspoon sea salt, 1/2 heaping cup gruyere
- While the mixer is on, combine the cream sauce with gruyere in the same pot as the potatoes. Beat until smooth and fluffy. Adjust salt to taste.Note: In this step, you can add a sprig of fresh thyme to seep into the cream. Remove the thyme once the cream is steaming.Thyme
Assemble the layers.
- Lightly spread the mashed potatoes in a medium size, shallow casserole dish with the back of a spoon. I used an oval, 11 inch long dish. Top with a layer of thinly sliced potatoes and gruyere. Cover with foil.1/2 heaping cup gruyere, 4 Yukon gold potatoes, thinly sliced
Bake.
- Bake for 25 minutes. Then, remove the foil and add parmesan on top. Bake for an additional 20 minutes uncovered or until golden and bubbly. Broil in the last 2-3 minutes for extra crisp. Best served hot. Keep covered in the oven until ready to serve.1/2 heaping cup parmesan
Notes
- This recipe is best served immediately. Make ahead option available in blog post. Mashed potatoes get dry when they cool because the starch molecules in the potatoes recrystallize and absorb moisture, causing once fluffy potatoes to become stiff and lose their fluffy texture. The butter and cream that keep them moist harden when cooled, thus contributing to the dryness.
- Use an electric hand mixer when mixing the mashed potatoes for best fluffy results.
Nutrition
The provided nutritional value above is an estimate per serving. 100% accuracy is not guarenteed. Please see Nutrition Information Disclaimer in our Privacy Policy.
Nutrition Information Disclaimer
This is PERFECT for Thanksgiving
Thank you! We hope you enjoy it as much as we do. 🙂