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. Spray a casserole dish with cooking spray and press the dough into the dish. Bake for 5-8 minutes, or until set and lightly golden.

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.

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 and spread over the ground beef layer.

Add small spoonfuls of salsa over the sour cream layer. 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.