Crock Pot Macaroni and Cheese

3 cups cooked macaroni
1 tbsp butter, melted
2 cups evaporated milk
3 cups shredded sharp process cheese
1/4 cup finely chopped green pepper
1/4 cup chopped onion
1 tsp salt
1/4 tsp pepper

toss macaroni with butter or margarine. Add remaining ingredients. Pour into lightly greased crock-pot. Cover and cook on high 2-3 hours, stirring once or twice