In a skillet, cook ground beef and chopped onion over medium heat until beef is browned. Drain excess fat.
Add garlic powder to the beef mixture and stir well.
In a baking dish, layer half of the tortillas, followed by half of the beef mixture, half of the sour cream, half of the enchilada sauce, and half of the shredded cheese. Repeat layers.
Bake in preheated oven for 30 minutes, or until cheese is melted and bubbly.
Let cool for a few minutes before serving.
Notes:
Feel free to add some chopped green chilies or olives for extra flavor.