Cheesy Mashed Potato Gratin

Name: Cheesy Mashed Potato Gratin with Gruyère and Fontina
Prep time: 10 min
Cook time: 35 min
Total time: 45 min
Yield: 4 servings
Cuisine: American
Ingredients: 2 lbs Yukon Gold potatoes; salt, to taste; 4 tbsp unsalted butter, divided; 2 cups whole milk, warmed and divided; 2 tbsp all-purpose flour; 1/2 cup Gruyère cheese, shredded; 1/2 cup Fontina cheese, shredded; 1 tbsp fresh chives, chopped, for garnish

Cheesy Mashed Potato Gratin combines riced Yukon Gold potatoes with a béchamel-based Gruyère and Fontina cheese sauce, then broiled until bubbly and golden. This restaurant-caliber technique delivers silky mashed potatoes with a rich, browned cheese topping.

🌍American 🏷️Mashed potatoes 🏷️Cheesy potatoes 🏷️Potato gratin 🏷️Side dish Comfort food

🏷️

🏷️Yukon gold potatoes

-0:00

thatdudecancookonTikTok

Total

45 min

Servings

4

Difficulty

Medium

Est. Cost

$17–$28

Recipe Source

View original recipe

From TikTok · by thatdudecancook

-0:00

thatdudecancookonTikTok

Ingredients

2 lbs Yukon Gold potatoes
salt, to taste
4 tbsp unsalted butter, divided
2 cups whole milk, warmed and divided
2 tbsp all-purpose flour
1/2 cup Gruyère cheese, shredded
1/2 cup Fontina cheese, shredded
1 tbsp fresh chives, chopped, for garnishoptional

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Instructions

1
Peel the potatoes and chop them into uniform pieces. Place them in a large pot and cover with cold water.
2
Add a generous amount of salt to the water and bring to a boil. Cook until the potatoes are fork-tender.
3
Drain the potatoes well. Pass the hot potatoes through a potato ricer into a large mixing bowl.
4
Season the riced potatoes with salt. Add about 2 tablespoons of butter and about 1/2 cup of warm milk. Gently fold everything together with a spatula until just combined. Do not overmix.
5
In a separate saucepan over low heat, melt the remaining 2 tablespoons of butter. Whisk in the flour to create a roux and cook for 5 minutes, stirring constantly.
6
Increase the heat slightly and gradually whisk in the remaining 1.5 cups of warm milk until you have a smooth béchamel sauce.
7
Gradually add the shredded Gruyère and Fontina cheese to the sauce, whisking continuously until the cheese is fully melted and the sauce is smooth and creamy.
8
Spread the mashed potatoes in an even layer in an oven-safe skillet or baking dish.
9
Pour the cheese sauce evenly over the top of the mashed potatoes.
10
Place the dish under the broiler for a few minutes, until the top is golden brown and bubbly in spots. Watch carefully to prevent burning.
11
Remove from the broiler and garnish with freshly chopped chives before serving.

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Tips & Notes

Pro tips

Warm the milk before adding to the roux to prevent lumps and ensure a silky sauce.
Shred cheese by hand rather than using pre-shredded varieties, which contain anti-caking agents that impede melting.
Watch the broiler closely—the cheese can go from golden to burnt in seconds. Position the rack 4–6 inches from the heating element.
Rice the potatoes while still hot for the smoothest texture; cold potatoes are harder to press through the ricer.

Substitutions

Yukon Gold → russet potatoes (starchier, slightly less creamy; reduce milk by 2 tablespoons)
Gruyère and Fontina → aged cheddar or Emmental (adjust 1:1 by weight)
Whole milk → heavy cream mixed with chicken or vegetable stock (richer but thinner sauce)
Fresh chives → fresh thyme or parsley (similar garnish effect)

Storage & make-ahead

Refrigerate covered up to 3 days. Reheat gently in a 350°F oven until warmed through, about 15 minutes, or broil briefly to re-crisp the cheese top.

Equipment

ricer or food mill · whisk · broiler-safe baking dish

Common Questions

Why rice the potatoes instead of mashing?

Ricing creates a finer, more uniform texture that prevents gluey or lumpy mashed potatoes and allows the creamy cheese sauce to coat evenly.

Can I make this dish ahead of time?

Yes. Prepare the mashed potatoes and cheese sauce, assemble in the baking dish, cover, and refrigerate up to 24 hours. Add 2–3 minutes to broiling time if baking from cold.

What cheese can I substitute if I don't have Gruyère or Fontina?

Raclette, Emmental, or aged cheddar work well. Avoid pre-shredded cheese, which contains anti-caking agents and won't melt as smoothly.

How do I know when the gratin is done broiling?

The cheese topping should be golden brown and bubbling around the edges, about 2–4 minutes depending on broiler intensity. Watch closely to avoid burning.