1. Preheat oven to 350°F. In 2-quart saucepan over medium heat, into melted butter or margarine, stir flour until smooth. Stir in onion, salt, and chili powder. Slowly stir in milk; cook, stirring constantly, until mixture thickens.
2. In colander, rinse and drain hominy well; stir into sauce. Pour mixture into 1 1/2-quart casserole. Sprinkle with cheese. Bake 20 to 25 minutes, until heated through.