HEAT oven to 350°F.
BEAT cream cheese in small bowl with mixer until creamy. Add 1 cup cheddar and onions; mix well. Spread down centers of tortillas; roll up.
PLACE, seam-sides down, in 11x7-inch baking dish; top with salsa. Cover.
BAKE 20 to 25 min. or until heated through. Sprinkle with remaining Cheddar.