Cook squash in a steamer (or boil) until soft - about 10 minutes. Drain and set aside.

In a skillet, cook bacon until done. Drain fat, and set aside. Melt butter and fry onions until soft. Stir in cornstarch and pepper, stirring until smooth. Add broth and continue cooking another 1-2 minutes or until sauce is thick. Remove from heat and add cheese. Stir until smooth.

In round casserole dish arrange half of the squash and top with half of the cheese mixture and half of the bacon. Repeat layers, then bake at 350°F for 30 minutes.