Combine Queso Bravo Cheese Dip, chili powder, cumin and oregano in mixing bowl fitted with paddle attachment; beat until combined. Slowly beat in tomatoes and stock until mixed well. Beat in chicken and pepper and onion blend until evenly distributed.
To build casseroles, place 2 tortilla pieces in 8-ounce microwave-safe containers; top with 1.5 ounces (about 3 tablespoons) chicken mixture. Repeat to make 4 layers. Top with generous 0.75 ounce (scant 1/4 cup) shredded cheese; cover. Hold cold for take-out.
To eat, loosely cover conainer; microwave 2-4 minutes or until temperature reaches 165°F. Let stand 2 minutes before eating.