Cheesy Cauliflower Potato Gratin (Printer-friendly)

Creamy baked cauliflower and potatoes in a rich cheese sauce, perfect for a comforting side dish.

# What You Need:

→ Vegetables

01 - 1 lb Yukon Gold potatoes, peeled and thinly sliced
02 - 1 lb cauliflower florets
03 - 1 small onion, finely chopped
04 - 2 cloves garlic, minced

→ Dairy

05 - 1 cup whole milk
06 - 1 cup heavy cream
07 - 1½ cups grated Gruyère cheese
08 - ¾ cup grated Parmesan cheese
09 - 2 tbsp unsalted butter

→ Pantry

10 - 2 tbsp all-purpose flour
11 - ½ tsp ground nutmeg
12 - Salt and black pepper, to taste

→ Topping

13 - 2 tbsp breadcrumbs (optional)
14 - 1 tbsp melted butter (for breadcrumbs, optional)

# How to Make It:

01 - Preheat the oven to 375°F. Grease a 9x13 inch baking dish with butter.
02 - Bring a large pot of salted water to a boil. Add sliced potatoes and cauliflower florets; cook for 5 minutes until just tender. Drain thoroughly and set aside.
03 - Melt 2 tablespoons butter in a medium saucepan over medium heat. Add chopped onion and minced garlic; cook until softened, about 3 minutes.
04 - Stir in 2 tablespoons flour and cook for 1 minute, stirring constantly to form a roux.
05 - Gradually whisk in 1 cup whole milk and 1 cup heavy cream. Simmer gently, whisking constantly, until sauce thickens, about 4 to 5 minutes.
06 - Remove from heat. Stir in Gruyère, ½ cup Parmesan, ground nutmeg, salt, and black pepper until cheese melts and sauce is smooth.
07 - In the prepared baking dish, layer half of the potatoes and cauliflower. Pour half of the cheese sauce over the vegetables. Repeat layering with remaining potatoes, cauliflower, and cheese sauce.
08 - Sprinkle the top evenly with remaining Parmesan cheese. Optionally, mix breadcrumbs with melted butter and evenly scatter on top for a crunchy crust.
09 - Bake for 40 to 45 minutes until the top is golden brown and sauce is bubbly. Remove from oven and let rest for 10 minutes before serving.

# Expert Tips:

01 -
  • It's the kind of side dish that steals the spotlight and tastes far more impressive than the effort requires.
  • The combination of creamy sauce and golden-brown top hits all the comfort zones at once.
  • Works beautifully as a vegetarian main course when you're feeding people who actually enjoy vegetables.
02 -
  • Don't skip the initial 5-minute blanch of the potatoes and cauliflower—it ensures they're tender enough to eat but sturdy enough not to disintegrate in the oven.
  • If your sauce looks thin, let it simmer a minute or two longer; it thickens more as it cools slightly, and you can always add a tiny bit more flour whisked with cream if needed.
  • The 10-minute rest after baking is not just tradition—it lets the layers set so each serving holds together instead of sliding across the plate in a creamy puddle.
03 -
  • Use a mandoline or the slicing blade on your box grater for potatoes that are perfectly thin and uniform—it saves time and ensures even cooking.
  • Make the sauce a little thinner than you think it needs to be; it thickens slightly as everything bakes and cools, and you want it creamy, not stiff.

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