Impossible Taco Pie - cooking recipe

Ingredients

1 lb. ground beef, venison or turkey
1/2 c. chopped onion
1 envelope taco seasoning
4 eggs
2 c. milk
1 1/3 c. Bisquick baking mix
2 tomatoes, sliced
1 c. Cheddar cheese, shredded

Preparation

Baking Temperature: 400\u00b0.
Baking Time: 45 minutes, divided.