Heat soup, milk, chiles and Velveeta in saucepan until smooth. Fill tortillas with some chicken, cheddar cheese, onion and a spoonful of soup/cheese mixture. Roll up and place in a 9x13-inch baking pan. Finish with remaining tortillas. Pour remaining sauce over enchiladas and top with rest of cheddar cheese. Bake at 350 degrees for 30-35 minutes.
Fancy Shred Cheddar Cheese for a lower fat version of recipe.