2 lbs. hamburger
1/2 c. onion, chopped
1 to 2 pkgs. taco seasoning mix
2 c. Monterey Jack cheese, shredded
2 1/2 c. milk
1 1/2 c. Bisquick
6 eggs

In skillet, cook meat and onion until brown. Drain. Stir in seasoning mix. Spread beef mixture in lightly greased 9 x 13 inch pan. Sprinkle with cheese. In mixing bowl beat remaining ingredients until smooth. Pour over meat and cheese. Bake at 400 degrees for 45 to 60 minutes or until golden brown and knife inserted in center comes out clean. Let stand 5 minutes before cutting.