Preheat oven to 350 degrees.
Heat a large skillet over medium-high heat.
Add ground beef, onion and taco seasoning; cook until meat is no longer pink.
Drain fat from beef and onion mixture.
Grate cheeses into a large bowl and combine.
Pour about 1/2 cup of enchilada sauce into the baking dish to cover the bottom.
Lay tortilla on a flat surface and spoon ground beef mixture down the middle, top with about 1/8 cup of cheese.
Roll up tortilla and place, seam side down, in the baking dish.
Repeat with remaining tortillas.
Top enchiladas with remaining enchilada sauce and cheese.
Bake for 15-20 minutes or until heat through and cheese has melted.