Preheat the Oven: Set the oven to 350℉.

Cook the Ground Beef: Heat a skillet over medium-high heat. Add the ground beef and break it apart with a spoon. Cook until no longer pink, stirring occasionally. Drain off any excess fat.

Prepare the Biscuit Dough: In a mixing bowl, combine the biscuit mix and water. Stir until well mixed, ideally using your hands for thorough blending. Spray a casserole dish with cooking spray and press the dough into the dish, spreading it out to the edges. Bake in the preheated oven for 5-8 minutes, or until the dough is set and lightly golden. Set aside, but keep the oven on.

Cook the Vegetables: Add chopped onions and red bell pepper to the cooked ground beef. Stir and cook for about 4 minutes. Add taco seasoning and mix well. Remove from heat.

Assemble the Layers: Spread the cooked ground beef mixture evenly on top of the baked biscuit layer.

Prepare the Sour Cream Layer: In a medium bowl, combine sour cream, mayonnaise, drained green chiles, ¾ cup shredded cheese, and garlic powder. Mix until smooth. Carefully spread this mixture over the ground beef layer.

Add Salsa and Cheese: Add small spoonfuls of salsa over the sour cream layer (no need to spread it out). Sprinkle the remaining shredded cheese evenly on top.

Bake: Place the casserole back in the oven, uncovered, and bake for 30 minutes or until hot and bubbly.