Step 1: Prepare the Meatloaf Mixture
Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking dish.
In a large bowl, mix the ground beef, bread crumbs, milk, egg, ranch seasoning mix, garlic powder, and onion powder until well combined.
Step 2: Assemble the Casserole
Press the meat mixture evenly into the prepared baking dish to form a meatloaf layer.
Sprinkle cheddar cheese evenly over the meat mixture.
Top with crushed Doritos, spreading them out evenly across the casserole.
Step 3: Add Sour Cream and Mozzarella
Dollop sour cream over the top and spread it out gently.
Sprinkle mozzarella cheese on top.
Step 4: Bake the Casserole
Bake in the preheated oven for 35–45 minutes, or until the meatloaf is fully cooked (internal temperature should reach 160°F).
Let the casserole cool for a few minutes before slicing and serving.