BRING crumbles, sauce and water to boil in large skillet on medium-high heat; stir in pasta. Simmer on medium-low heat 20 min. or until pasta is tender and crumbles are cooked through (160ºF), stirring occasionally.
STIR in ricotta; cover. Simmer 5 min. Stir in 1/2 cup mozzarella; top with remaining mozzarella. Remove from heat.
LET stand, covered, 5 min. or until mozzarella is melted.