Brown:

1 lb. hamburger
1 sm. chopped onion

Drain. Layer in 9 x 9 inch baking dish.

In blender mix:

1 1/2 c. milk
1 egg
1 tsp. pepper
2 tsp. salt
3/4 c. Bisquick

Pour over burger. Top with 1 cup shredded cheese and sliced tomatoes. Bake at 350 degrees for 35 to 45 minutes.