Grease a 2-quart baking dish. Heat oven to 350°.

Cook the pasta in boiling water following package directions. Drain and rinse; set aside.

In a medium saucepan over medium-low heat, melt butter. Add the flour and cook, stirring, until smooth and bubbly. Add the milk or half-and-half and Boursin cheese. Cook, stirring, until hot and thickened. Add the cheese and peppers. Cook, stirring, until cheese has melted. Add salt and pepper, to taste. Combine the sauce with the pasta and stir to blend. Spoon into prepared baking dish.

Toss melted butter and bread crumbs together and sprinkle over the casserole. Bake for about 25 minutes, or until bubbly and lightly browned.