Preheat the oven to 350℉.

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 excess fat.

In a mixing bowl, combine biscuit mix and water. Stir until well blended. Spray a 9×13-inch casserole dish with cooking spray. Press dough into the dish and spread evenly to the edges. Bake for 5–8 minutes until set and lightly golden. Remove from oven, keeping oven on.

Add chopped onion and red bell pepper to the cooked beef. Stir and cook for 4 minutes. Add taco seasoning and mix well. Remove from heat.

Spread the beef mixture evenly over the baked biscuit base.

In a medium bowl, mix sour cream, mayonnaise, drained green chiles, ¾ cup shredded cheese, and garlic powder until smooth. Spread this mixture carefully over the beef layer.

Spoon salsa in small amounts over the creamy layer. Sprinkle the remaining shredded cheese evenly on top.

Bake uncovered for 30 minutes, until the casserole is hot, bubbly, and golden.