Preheat the oven to 375°F (190°C). Lightly spray a 9x13-inch casserole dish with nonstick cooking spray.
In a medium bowl, mix the Red Lobster Cheddar Bay Biscuit Mix (including the seasoning packet) and 3/4 cup cold water until just combined. Spread the dough evenly in the casserole dish. If the dough is sticky, spray your hands with cooking spray to help spread it out evenly.
Bake the biscuit dough at 375°F (190°C) for 5-8 minutes until set. Remove from the oven and set aside.
In a large skillet over medium heat, cook the ground beef and diced onion until the beef is browned. Drain excess grease if needed.
Stir in the taco seasoning, 1/4 cup water, drained fire-roasted diced tomatoes, and undrained diced green chilies. Let it simmer for 2-3 minutes, stirring occasionally.
Spread the beef mixture evenly over the partially baked biscuit layer in the casserole dish.
In a small bowl, combine mayonnaise, sour cream, and 1 cup shredded Colby Jack cheese. Spread this mixture evenly over the beef layer.
Sprinkle the remaining 1 cup shredded Colby Jack cheese over the top.
Bake the casserole for 30 minutes until the cheese is melted and bubbly. Let it cool for 5 minutes, then garnish with dried parsley flakes before serving. Enjoy!
Notes
You can customize this casserole by adding toppings like sliced jalapeños, diced avocado, or a dollop of salsa.