4 tbsp. butter
2/3 c. chopped onion, or to taste
4 tbsp. flour
3 c. milk
2 c. chopped cooked broccoli
4 slices cheese (preferably Velveeta), cubed
1 tsp. salt
Dash of pepper

Melt butter in saucepan. Add onion and cook until tender. Blend in flour until mixture is smooth. Add milk, broccoli, cheese, and seasonings. Cook until mixture thickens and cheese is melted, stirring constantly.