In a large saucepan, combine the first six ingredients. Bring to a boil. Reduce heat; simmer, uncovered, for 4-5 minutes or until thickened, stirring occasionally. Spoon 2 tablespoons sauce over each tortilla.
In a large bowl, combine the Monterey Jack, 2 cups cheddar cheese, onions, sour cream, parsley, salt and pepper. Place about 1/3 cup down the center of each tortilla. Roll up and place seam side down in two greased 13-in. x 9-in. baking dishes. Pour remaining sauce over top.
Bake, uncovered, at 350° for 20 minutes. Sprinkle with remaining cheddar cheese. Bake 4-5 minutes longer or until cheese is melted. Garnish with lettuce, olives and sour cream if desired.