Dijon Scalloped Potatoes

1 medium onion, chopped
6 oz. PHILADELPHIA Cream Cheese, softened
1 can (14-1/2 oz.) chicken broth
1 Tbsp. GREY POUPON Dijon Mustard
1-1/2 lb. potatoes, peeled, thinly sliced (about 3 medium potatoes)
35 RITZ Crackers, crushed (about 2 cups)
3 Tbsp. KRAFT 100% Grated Parmesan Cheese
2 Tbsp. butter, melted
2 tsp. chopped fresh parsley

PREHEAT oven to 350°F. Lightly spray large skillet with cooking spray; heat on medium-high heat. Add onion; cook 5 to 7 min. or until tender, stirring often. Add cream cheese, broth and mustard; mix well. Remove from heat; set aside.
LIGHTLY spray 13x9-inch baking dish with cooking spray. Toss potatoes with cream cheese mixture; spoon into prepared pan. Combine crushed crackers, Parmesan cheese, butter and parsley; sprinkle evenly over potatoes.
BAKE 50 min. to 1 hour or until potatoes are tender. Let stand 5 min. before serving.