Start by preheating your oven to 375°F (190°C). While the oven heats, mix shredded chicken, cooked rice, black beans, shredded cheese, sour cream, enchilada sauce, and spices (chili powder, cumin, and garlic powder) in a large bowl. Stir until everything is well combined, creating a flavorful, hearty filling.
Lay your tortillas flat on a clean surface. Spoon a generous portion of the filling into the center of each tortilla. Fold the sides in, then roll tightly to form a burrito. The tighter the roll, the better it holds together during baking.
Grease your baking dish lightly, then place each burrito seam-side down into the dish. Once all the burritos are in, pour the reserved enchilada sauce evenly over the top. Sprinkle the remaining shredded cheese over the sauce for that iconic smothered topping.
Bake the burritos uncovered for about 20-25 minutes. Once the cheese is melted and bubbly, remove the dish from the oven. The enchilada sauce will be piping hot, so allow them to cool for a few minutes before serving.