Impossible Cheeseburger Pie

1 lb. ground beef
1/2 cup chopped onions
1/2 teaspoon salt
1/4 teaspoon pepper
1 and 1/2 cups milk
3 eggs
3/4 cup Bisquick or other mix
1 to 2 cups Cheddar cheese

Preheat oven to 400 degrees.
Grease pie plate.

Cook ground beef and onion until done. Drain.
Add salt and pepper.

Spread in pie plate.
Beat milk, eggs, and baking mix until smooth.
Pour over hamburger mixture.
Bake 30 minutes. 
Sprinkle with cheese.
Return to oven for 5 to 10 minutes, or until knife 
inserted in center comes out clean.
Cool 5 minutes before serving.