Zesty Cheeseburger Mac Casserole

1 pkg. (16 oz.) frozen vegetable blend with broccoli, carrots, cauliflower (3 cups)
1 pkg. (14 oz.) KRAFT Deluxe Macaroni & Cheese Dinner Made With 2% Milk Cheese
3/4 cup fat-free milk
1/4 cup KRAFT Light Zesty Italian Reduced Fat Dressing (I used fat free)
1 lb. extra lean ground beef, cooked, drained
1 cup KRAFT 2% Milk Shredded Reduced Fat Sharp Cheddar Cheese, divided
PREHEAT oven to 375°F. Place frozen vegetables in colander in sink. Cook Macaroni as directed on package. Pour cooked macaroni over vegetables in colander to drain and quickly thaw vegetables.
RETURN macaroni and vegetables to same saucepan. Add Cheese Sauce, milk and dressing; mix well. Add cooked meat and 1/2 cup of the Cheddar cheese; mix well. Spoon into 2-qt. round casserole dish; cover with foil.
BAKE 35 min. or until heated through. Uncover; top with remaining 1/2 cup Cheddar cheese. Bake an additional 3 to 4 min. or until cheese is melted.