Impossible Cheeseburger Pie

Why I Love This Recipe
This recipe is from Bisquick.
I've been making it a long time; and it's a hit with the guys in my house.
Ingredients You'll Need
1 lb Ground beef
1 1/2 c Onions; chopped
1/2 ts Salt
1/4 ts Pepper
3 Eggs
3/4 c Bisquick
2 Tomatoes; sliced
1 c Cheddar, shred
1 1/2 c Milk
Directions
Preheat oven to 400.
Can be topped with crisply cooked bacon.
Grease pie plate, 10x1 1/2 inch, or sq. baking dish, 8x8, or
6 10 oz. custard cups.
Cook and stir gr. beef and onion in 10 inch skillet over med.
heat until beef is brown; drain. Stir in salt and pepper. Spread
in pie plate.
Beat milk, eggs and baking mix 15 sec. in blender on high speed,
1 min. with wire whisk or hand beater or until smooth. Pour
into pie plate.
Bake 30 min. Top with tomato slices; sprinkle with cheese.
Bake 5-8 min. or til knife comes out clean.
Cool 5 min