Preheat oven to 350°F. Spray a 9 x 13 inch casserole dish with cooking spray and set aside.

Heat a large skillet over medium-high heat. Add ground beef and break apart with a spoon. Cook for 6-8 minutes, stirring occasionally, until no pink remains and meat is browned. Drain excess fat thoroughly.

In a medium mixing bowl, combine biscuit mix and water. Stir with a spoon, then knead with your hands until dough comes together smoothly. Press dough into prepared casserole dish, spreading evenly to edges and slightly up the sides.

Bake biscuit crust for 5-8 minutes until set and lightly golden around edges. Remove from oven but leave oven on.

Return drained beef to skillet over medium heat. Add chopped onion and red bell pepper. Cook for 4-5 minutes, stirring frequently, until vegetables soften. Add taco seasoning and stir well to coat. Cook for 1 minute more, then remove from heat.

Spread seasoned beef mixture evenly over the par-baked biscuit crust, pressing down gently to create an even layer.

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

Drop small spoonfuls of salsa randomly across the sour cream layer without spreading. Sprinkle remaining ¾ cup shredded cheese evenly over the top.

Bake uncovered for 30 minutes until cheese is melted and golden, edges are bubbly, and center is hot. Let rest 5 minutes before serving.