In a large skillet, cook ground beef over medium heat until browned. Drain excess fat.
Add enchilada sauce to the skillet with the ground beef and mix well.
Place a small spoonful of the ground beef mixture onto a tortilla. Top with some shredded cheese and chopped onions. Roll up the tortilla tightly and place it in a greased baking dish. Repeat with the remaining tortillas and filling.
Pour any remaining sauce over the enchiladas and sprinkle with additional cheese.
Bake in the preheated oven for about 20 minutes, or until the cheese is melted and bubbly.