Deep-Dish Taco Squares

1/2 pound lean ground beef
1/4 cup chopped onion
2 tablespoons taco seasoning mix
1 cup baking mix
1/4 cup cold water
1/2 cup sour cream
1/3 cup mayonnaise or salad dressing
1/2 cup shredded sharp cheddar cheese
3/4 cup chopped tomato
1 can (4.5 oz) chopped green chiles

1. Heat oven to 350 degrees. Spray 8 inch baking dish with cooking spray. Brown beef and cook onion. Drain. Stir in taco seasoning mix.
2. In small bowl mix baking mix and water until soft dough forms. Using fingers dusted with baking mix pat dough in bottom and up sides of baking dish.
3. In same bowl mix sour cream, mayonnaise and cheese until blended.
4. Layer beef mixture, tomato and chiles over dough. Spoon sour cream mixture over top.
5. Bake 25 to 30 minutes or until edges of dough are light brown.