Preheat the oven to 350°F.

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.

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.

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.

Spread the cooked ground beef mixture evenly on top of the baked biscuit 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 small spoonfuls of salsa over the sour cream layer (no need to spread it out). Sprinkle the remaining shredded cheese evenly on top.

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