- 2 tablespoons olive oil
- 1 medium onion, sliced
- 1 medium red bell pepper, sliced
- 8 ounces sliced fresh mushrooms
- 1/2 teaspoon salt, divided
- 1/4 teaspoon black pepper
- 6 tablespoons all-purpose flour
- 3 cups low-fat (1%) milk, heated
- 1/2 cup shredded Cheddar cheese
- 1/4 cup shredded Romano cheese
- 7 cups frozen broccoli florets, thawed, well drained on paper towel
- 1 cup fresh whole-grain bread crumbs
- 1 tablespoon butter, cut into bits
- Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 2-quart baking dish.
- Heat oil in a large skillet over medium-high heat. Cook onion, bell pepper, mushrooms, 1/4 teaspoon salt, and black pepper, stirring frequently, until mixture begins to brown, 12 to 15 minutes.
- Sprinkle flour over mushroom mixture and cook, stirring, 1 minute. Add remaining 1/4 teaspoon salt and milk and bring to a boil, stirring until smooth. Boil, stirring frequently, until slightly thickened, about 3 minutes. Stir in cheddar and 2 tablespoons romano. Stir in broccoli and pour mixture into prepared baking dish.
- Toss bread crumbs with remaining 2 tablespoons romano and sprinkle over top. Dot with butter.
- Bake, uncovered, until crumbs are golden and casserole is bubbling, about 40 minutes. Cool 5 minutes before serving.