Summer Squash Bake

1-1/2 pounds of summer squash
1/4 cup of chopped onion
1/4 cup of butter
3 eggs, beaten
1 cup of milk
1/2 cup of grated Parmesan cheese

Simmer the squash and onion until soft. (approx 10 minutes) drain.
Mix butter with squash.
Add milk, Parmesan and eggs.
Pour into casserole dish. Bake at 350 degrees for 40 minutes.