In a large bowl, combine 3 cups shredded cheddar cheese and sour cream. Set aside 2 tablespoons olives and 2 tablespoons onions. Add remaining olives and onions to cheese mixture; mix well. Spoon 1/2 cup down the center of each tortilla. Roll up and place seam side down in a greased 13x9-in. baking dish. Pour enchilada sauce over the top. Sprinkle with remaining cheese.
Cover and bake at 325° for 25-30 minutes or until heated through and cheese is melted. Sprinkle with reserved olives and onions.