This casserole has a twist compared to other cheesy casseroles, because the cheese is Swiss and Parmesan. It really changes up the flavor. And to save myself some time, I totally used frozen broccoli and cauliflower. But this would work just the same with fresh veggies. If you use fresh veggies, place them in a pot of boiling salted water for 3 minutes. Drain and immediately shock in a bowl of ice water. This stops the cooking and helps the veggies keep their color. Set the veggies aside. If you are using frozen veggies, let them defrost first and drain the excess water. If you don't drain them, you will end up with soggy veggies.
3 cups broccoli florets
2 cups cauliflower florets
1 1/2 cups bread crumbs (I used Italian)
2 Tablespoons butter, melted
3 Tablespoons butter
2 Tablespoons flour
2 1/4 cups milk (use 2% or whole)
1 Tablespoon Dijon mustard
2/3 cups shredded Swiss cheese
2/3 cups shredded Parmesan cheese
Preheat the oven to 375 degrees.
Combine the bread crumbs and melted butter until coated. Set aside.
Melt the remaining 3 Tablespoons of butter in a large saucepan over medium heat. Whisk in the flour, then cook for 1 minute. Whisk in the milk and Dijon, cooking until the sauce slightly thickens, about 8 minutes. Make sure the mixture does not come to a boil. Add the cheeses and stir until completely melted. Season with salt and pepper. Stir in the broccoli and cauliflower into the sauce. Make sure the veggies are completely coated, then pour into a 9x13 pan or a 2-quart baking dish.
Sprinkle the crumb topping over the casserole. Bake for about 35 minutes, or until the casserole is bubbly. Let sit for 10 minutes before serving.