Drained French green beans; spread evenly in casserole dish.
Melt butter in a small saucepan. Stir in flour. Add sour cream, sugar, 1 tsp salt and pepper to taste, and instant minced onions. Mix well over medium heat, do not boil. Spread mixture over green beans. Top with shredded cheddar cheese. Top again with corn flake crumbs. Drizzle melted butter over crumbs.