Mashed Potato Gratin
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This mashed potato gratin combines two favorite potato textures in one dish. A base of creamy, cheesy mashed potatoes gets topped with thin sliced potatoes tossed in garlic butter and Parmesan, then baked until the top layer turns golden and slightly crisp.
It’s not a hard recipe to make, but it is a bit time consuming since you’re essentially making mashed potatoes and then prepping and slicing a second batch for the topping, worth planning for if you’re making this alongside other dishes.
What You Need for This Recipe
For the mashed potato base:
- Baking potatoes (russet works well) form the mashed base.
- Butter and half and half create a rich, creamy texture.
- Shredded cheddar cheese adds sharp, melty flavor throughout.
- Salt and black pepper season the potatoes.
For the gratin topping:
- Baking potatoes, sliced thin, layer on top of the mashed potatoes.
- Melted butter and minced garlic coat the sliced potatoes with flavor.
- Shredded Parmesan cheese, divided, gets mixed into the sliced potatoes and sprinkled on top partway through baking.
- Fresh chives, optional, finish the dish after baking.
How to Make Mashed Potato Gratin
Mashed potatoes: Peel and slice the potatoes into 1 inch cubes. Place them in a large saucepan and cover with cold water, making sure the water sits at least 1 inch above the potatoes. Add salt to the water. Heat over medium high heat, stirring occasionally, until the potatoes are fork tender. Drain.
In the same warm saucepan, add the butter and half and half, stirring well until melted. If needed, turn the heat to low and stir constantly until fully melted. Add the potatoes back to the pan and mash. Stir in the cheddar cheese, then season with salt and pepper.
Grease a 2 and a half quart baking dish with nonstick cooking spray and spread the mashed potatoes into the dish. Set aside.
Gratin topping: Peel the gratin potatoes, slice them lengthwise, then cut into 1/8 inch half moons. Add the potato slices to a bowl and mix with the melted butter, garlic, and half of the Parmesan cheese. Season with salt and pepper and mix well.
Place the potato slices, cut side down, on top of the mashed potatoes, layering them across the pan. Cover with foil and bake at 400 degrees for 20 minutes.
Remove from the oven and discard the foil.
Add the remaining reserved Parmesan cheese and return to the oven for 40 minutes. Remove from the oven and let stand for 10 minutes before serving, topped with fresh chopped chives.
Serves 8.
Tips for the Best Mashed Potato Gratin
Plan for the extra time. Since you’re making two separate potato components, this takes a bit longer than a standard mashed potato or gratin recipe on its own. It’s worth the effort for the layered texture, but budget accordingly if you’re making it alongside a full meal.
Slice the gratin potatoes evenly. Consistent 1/8 inch slices help the topping layer cook evenly and gives you that classic gratin look on top.
Let it rest before serving. The 10 minute stand time helps everything set so the layers hold together when you serve it.
More Potato Side Dishes to Try
If you love a good potato side dish, check out our mashed potatoes with cream cheese for a steakhouse style version, or our scalloped potatoes and ham for a heartier baked option.
Our married mashed potatoes blend sweet and russet potatoes for a fun twist, and our cheesy potato casserole is another crowd pleasing potato bake worth trying.
Mashed Potato Gratin
Equipment
- 2 1/2 quart baking dish
Ingredients
Mashed Potatoes:
- 3.5 lbs baking potatoes about 5 to 6 potatoes
- 1 tablespoon salt
- 6 tablespoons butter sliced
- 2/3 cup half and half
- 1 1/2 cups shredded cheddar cheese
- black pepper
Gratin:
- 1.5 lbs baking potatoes about 2 potatoes
- 2 tablespoons butter melted
- 1 clove garlic minced
- salt and pepper
- 1/2 cup shredded Parmesan cheese divided
- chopped fresh chives optional for serving
Instructions
Mashed Potatoes
- Peel and slice potatoes into 1 inch cubes. Place into a large saucepan and cover with cold water, making sure water is at least 1 inch above the potatoes. Add salt to the water. Heat over medium high heat, stirring occasionally, until potatoes are fork tender. Drain potatoes.
- In the same warm saucepan, add butter and half and half and stir well until melted. If necessary, turn heat to low and stir constantly until butter is melted. Add potatoes to the pan and mash. Stir in cheese, season with salt and pepper.
- Grease a 2 1/2 quart baking dish with nonstick cooking spray and spread mashed potatoes into the baking dish. Set aside.
Gratin
- Peel gratin potatoes and slice potato lengthwise and then into 1/8 inch half moons. Add potatoes to a bowl and mix with melted butter, garlic, and half of the Parmesan cheese. Season with salt and pepper. Mix well.
- Place potato slices, cut side down, on top of the mashed potatoes, layering them in the pan.
- Cover with foil and bake at 400 degrees for 20 minutes. Remove from oven and discard foil. Add remaining reserved Parmesan cheese and return to the oven for 40 minutes.
- Remove from oven and let stand for 10 minutes before serving topped with chopped fresh chives.
Notes
Nutrition
Nutritional Disclaimer: The nutritional data provided here is auto-calculated and intended for your convenience only. As it’s generated via automation, its accuracy may be compromised. For precise nutritional insight, please compute the values utilizing the actual ingredients in your recipe through your chosen nutrition calculator or application.
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