Cauliflower and Potato Casserole

4.32 from 41 votes

Cauliflower and Potato Casserole

Cauliflower and potato casserole topped with creamy cheese sauce is a comfort food side dish. Whether you make it for a holiday or a weeknight dinner, it’s guaranteed to disappear fast!

Prep Time20

Cook Time55

Cooling Time10

Total Time1 25

Course: Casseroles, Sides & Vegetables

Cuisine: American

Servings:

Author: Rachel Gurk

Ingredients

For Roasted Vegetables:

1 head cauliflower, cut into small florets (about 8 cups cauliflower)
1 ½ pounds russet potatoes, peeled & diced into ½-inch chunks (about 4 cups)
2 tablespoons olive oil
1 teaspoon kosher salt
¼ teaspoon coarse ground black pepper

For Cheese Sauce:

3 tablespoons butter
3 tablespoons all-purpose flour
1 teaspoon garlic powder
½ teaspoon onion powder
½ teaspoon ground mustard (optional but recommended)
¼ teaspoon kosher salt
¼ teaspoon coarse ground black pepper
2 cups milk (I recommend whole milk or 2%)
1 cup shredded sharp cheddar cheese (see notes)
½ cup grated Parmesan cheese

For Topping:

½ cup panko breadcrumbs
2 tablespoons grated Parmesan cheese
1 tablespoon butter, melted

Instructions

Preheat oven to 375°F. Lightly grease a 9 x 13-inch baking dish.
In the prepared pan, toss cauliflower and potatoes in olive oil, salt, and pepper. Roast for 25 minutes.
1 head cauliflower, cut into small florets, 1 ½ pounds russet potatoes, peeled & diced into ½-inch chunks, 2 tablespoons olive oil, 1 teaspoon kosher salt, ¼ teaspoon coarse ground black pepper
Meanwhile, in a saucepan, melt butter over medium heat. Whisk in flour, garlic powder, onion powder, ground mustard, salt, and pepper; cook for 1 minute to form a roux. Slowly whisk in milk, stirring constantly until the sauce comes to a boil and is slightly thickened (5 to 6 minutes).
3 tablespoons butter, 3 tablespoons all-purpose flour, 1 teaspoon garlic powder, ½ teaspoon onion powder, ½ teaspoon ground mustard, ¼ teaspoon kosher salt, 2 cups milk, ¼ teaspoon coarse ground black pepper
Reduce heat to low, and gradually stir in the cheddar cheese and Parmesan (don't dump it in the sauce all at the same time). Stir until the cheese is melted and the sauce is smooth. Remove from heat.
1 cup shredded sharp cheddar cheese, ½ cup grated Parmesan cheese
Pour cheese sauce over the roasted cauliflower and potatoes and gently mix to coat.
To make the topping, in a small microwave-safe bowl, melt 1 tablespoon butter. Stir in the breadcrumbs and 2 tablespoons Parmesan cheese. Sprinkle the mixture evenly over the casserole.
½ cup panko breadcrumbs, 2 tablespoons grated Parmesan cheese, 1 tablespoon butter, melted
Bake for 30 to 35 minutes, or until golden and bubbly. Let rest 10 minutes before serving.

Video

Notes

Cauliflower: After you rinse the cauliflower, make sure to dry it fairly well. The florets can hold quite a bit of water and could make your casserole too juicy. A quick spin in your salad spinner does the job.
Potatoes: We recommend russet potatoes, but Yukon gold potatoes also work well. Although you can skip peeling the potatoes (especially the Yukon gold potatoes), we found that we preferred the potatoes peeled in this casserole.
Pro tip: For best results, shred your own cheddar cheese instead of using pre-shredded. Pre-shredded cheese has an anti-clumping additive and doesn't melt as smoothly. You can also substitute another type of cheese, if you prefer.
Topping: We use panko breadcrumbs which have a much coarser texture than regular breadcrumbs, so it gets nice and crispy. Homemade breadcrumbs would also work. If you prefer, you can skip the topping or try an alternative topping, such as crushed potato chips, cracker crumbs, additional shredded cheese, and so on.
Make it a meal: To add protein to this veggie dish, add diced cooked ham when you stir in the cheese sauce. You could also use cooked chicken, albacore tuna, or even browned ground beef.
Recipe retested and revised 8/2025.

Nutrition

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