Grease a 15 x 10 x 1" baking pan.
Stir egg, corn muffin mix and milk in bowl. With damp fingers pat in pan.
Bake at 400 for 10 minutes or until edges are lightly brown.
Cook beef. Drain. Add Taco mix and 3/4C salsa. Simmer uncovered 10 minutes.
Spread beans over cornbread.
Sprinkle with 1/2C cheese. Bake to melt the cheese 2 minutes.
Top with meat mixture, remaining cheese. Bake to melt the cheese 2 minutes.
Spread with sour cream.
Top with lettuce, scallion, remaining salsa.
Note: We did not put the sour cream, lettuce, extra salsa and scallion on. We had them available in small bowls on the table so the kids could make their own Tacos! :)