Brown the ground beef in a large skillet over medium heat, then drain any excess fat.

Add the chopped onion and minced garlic to the skillet and cook until softened, about 5 minutes.

Stir in the chili powder, cumin, salt, and black pepper, cooking for another minute until fragrant.

Preheat your oven to 375°F (190°C) and lightly grease a 9x13 inch baking dish.

Warm the corn tortillas slightly to make them pliable, either in the microwave or a warm skillet. Dip each tortilla into the enchilada sauce to coat.

Spoon a portion of the beef filling down the center of each tortilla, then sprinkle with a mix of cheddar and Monterey Jack cheeses. Roll up the tortillas and place them seam-down in the prepared baking dish.

Pour the remaining enchilada sauce over the rolled enchiladas and top with the remaining shredded cheese.

Bake for 20-25 minutes, or until the cheese is melted and bubbly and the enchiladas are heated through.

Garnish with sliced green onions and serve with sour cream on the side.