01 -
Preheat the oven to 375F. Grease a 9x13-inch baking dish with nonstick spray or a thin layer of oil.
02 -
Stir the biscuit mix, seasoning packet, and cold water in a medium bowl just until combined. Press the sticky dough evenly into the bottom of the prepared dish.
03 -
Bake the biscuit layer for 6-8 minutes, until the surface looks set but not browned. Remove the dish from the oven and keep the oven on.
04 -
Brown the ground beef and onion in a large skillet over medium heat, breaking the meat into small crumbles. Drain excess grease if needed.
05 -
Stir in taco seasoning, 1/4 cup water, drained tomatoes, and green chiles. Simmer for 2-3 minutes, until the mixture is saucy but not watery.
06 -
In a small bowl, mix sour cream, mayonnaise, and 1 cup of the shredded cheese until evenly combined.
07 -
Spread the beef mixture over the biscuit base. Spoon the creamy topping over the beef, then sprinkle with the remaining 1 cup cheese. Bake for 28-32 minutes, until bubbling and melted on top.
08 -
Let the casserole rest for 8-10 minutes before scooping. Garnish with parsley or green onion if using.