Stir together first 3 ingredients. Turn dough out onto a surface sprinkled with biscuit mix. Shape into a ball, and knead 3 to 4 times. Divide into 6 portions.
Invert 6 (6-ounce) custard cups several inches apart on a lightly greased baking sheet. (Or use an inverted muffin pan.) Coat outsides of cups with vegetable cooking spray.
Roll or pat each dough portion into a 6-inch circle. Place each on a custard cup; press into a bowl shape.
Bake at 450° for 10 to 12 minutes. Cool slightly; remove biscuit bowls to a wire rack.
Cook beef, onion, and bell pepper in a Dutch oven over medium heat until meat crumbles and is no longer pink; drain. Stir in tomatoes, beans, and chili powder.
Bring beef mixture to a boil; cover, reduce heat, and simmer 35 minutes. Spoon into biscuit bowls, and serve with desired toppings. Garnish, if desired.