Ingredients
Vegetables
- 4 cups medium broccoli florets (from 1 head broccoli)
- 4 cups medium cauliflower florets (from 1 head cauliflower)
- 3 medium carrots, thinly sliced
Cheese Sauce
- 3 tablespoons salted butter
- ⅓ cup all purpose flour
- 2 ⅓ cups whole milk
- 1 teaspoon garlic powder
- ½ teaspoon kosher salt, plus more to taste
- Lots of freshly ground black pepper
- 8 ounces sharp cheddar cheese, cut into small cubes
- ⅓ cup grated parmesan cheese
Topping
- ¾ cup panko breadcrumbs
- 1 tablespoon salted butter, melted
Other
- Nonstick cooking spray or olive oil, for greasing the baking dish
Instructions
- Prep your pan: Preheat your oven to 375°F (190°C). Grease a 2½-quart baking dish or an 11×7 inch baking pan with nonstick cooking spray or olive oil. Add the broccoli florets, cauliflower florets, and thinly sliced carrots evenly into the prepared baking dish. Set aside while you prepare the sauce.
- Make the roux: In a large skillet or pot over medium heat, melt 3 tablespoons of salted butter. Once melted, whisk in ⅓ cup of all-purpose flour to form a roux. Slowly add 2 ⅓ cups of whole milk a little at a time, whisking vigorously to avoid lumps. Bring the mixture to a gentle boil, then reduce the heat to low and let it simmer for a few minutes, stirring occasionally, until the sauce thickens to a gravy-like consistency. Stir in 1 teaspoon garlic powder, ½ teaspoon kosher salt, and plenty of freshly ground black pepper. Adjust consistency as needed by adding a splash more milk if too thick or an additional tablespoon of flour if too thin.
- Add the cheese: Stir 8 ounces of sharp cheddar cheese (cut into small cubes) and ⅓ cup grated parmesan cheese into the thickened sauce until fully melted and smooth. Taste and adjust seasoning by adding more salt and freshly ground black pepper as desired. The cheese sauce should be flavorful and slightly salty to complement the vegetables.
- Bake covered: Pour the cheese sauce evenly over the vegetables in the baking dish. Cover the dish tightly with foil and bake in the preheated oven for 30 minutes, allowing the veggies to soften and the flavors to meld.
- Make the breadcrumb topping: While the gratin bakes, combine ¾ cup panko breadcrumbs with 1 tablespoon melted salted butter in a medium bowl, mixing until the crumbs are evenly coated.
- Top and bake uncovered: After 30 minutes, remove the foil from the baking dish. Evenly sprinkle the buttered breadcrumb mixture over the top of the gratin. Return the dish to the oven and bake uncovered for an additional 20 to 30 minutes or until the breadcrumbs are golden brown and the vegetables are fork-tender. Serve warm, yielding 6 to 8 servings.
Notes
- For a lighter version, you can substitute whole milk with 2% milk, but the sauce may be slightly less rich.
- Make sure to cut the cheese into small pieces to help it melt evenly in the sauce.
- Feel free to add other vegetables like sliced bell peppers or mushrooms for variety.
- If the breadcrumb topping browns too quickly, cover loosely with foil halfway through the baking time.
- This gratin can be prepared a day ahead and refrigerated before baking for convenience.
- Prep Time: 15 minutes
- Cook Time: 50 minutes
- Category: Side Dish
- Method: Baking
- Cuisine: American
- Diet: Vegetarian
