Clara's Cauliflower Bake

1 head cauliflower
1 cup sliced mushrooms
1/4 cup diced green pepper
1/4 cup butter
1/3 cup flour
2 cups milk
salt and pepper to taste
1 c. shredded Swiss cheese
2 tbsp. chopped pimento

Break cauliflower into medium size flowerets. Cook in boiling water until crisp-tender, about 8 to 10 minutes. Drain. Sauté mushrooms and green pepper in butter in medium saucepan until tender. stir in flour. Gradually stir in milk. Cook and stir until smooth and thickened. Stir in cheese, salt, pepper, and pimento. Heat oven to 325°. Put half of the cauliflower into a buttered 2-quart casserole dish. Cover with half of the sauce. Then add remaining cauliflower and remaining sauce. Bake until hot and bubbly, about 15 minutes.
Serves 8 to 10.