Preheat your oven to 350°F (180°C) and lightly grease a 9×13-inch baking dish with cooking spray. In a medium bowl, mix the baking mix, milk, and 1 tablespoon of oil. Spread it evenly in the dish and bake for 10–15 minutes until lightly golden. Set aside.

Heat the remaining 1 tablespoon of oil in a large skillet over medium-high heat. Add the ground beef and cook, stirring occasionally, until almost cooked through. Stir in the diced onion, red bell pepper, taco seasoning, and salt. Continue cooking until the beef is fully browned and the onions are soft. Remove from heat.

In a medium bowl, combine the mayonnaise, sour cream, and 1 cup each of cheddar and pepper jack cheese. Mix until well combined.

Spoon the beef mixture over the baked biscuit base. Spread the diced tomatoes and green chiles on top, then add the creamy cheese mixture. Smooth it out evenly. Sprinkle the remaining cheese over the top.

Bake for about 30 minutes or until bubbly and golden brown. Let it rest for 10 minutes before serving to allow the layers to set.