cheeseburger pie

1 pound hamburger
1 chopped onion
salt and pepper to taste
1½ cup milk
¾ cup bisquick
3 eggs
1 can tomatoes, drained
1 cup shredded cheese

Brown hamburger and onions together.
Add salt and pepper.
Put in a greased 9x9 pan.
Combine milk, bisquick and eggs together.
Pour over hamburger.
Bake at 400 degrees for 25 minutes.
Add tomatoes and cheese.
Bake 10 minutes longer or until knife inserted in middle comes out clean.

I have no idea where this came from.
Made for Matt's parents for dinner Fall 2007