OLD FASHIONED MACARONI & CHEESE

3 Tbsp. butter or margarine
2 Tbsp. flour
1/2 tsp. salt
2 cups milk
2 cups KRAFT Shredded Sharp Cheddar Cheese, divided
1 pkg. (7 oz.) elbow macaroni (1-3/4 cups), cooked, drained

PREHEAT oven to 350°F. Melt butter in large saucepan on low heat. Add flour and salt; mix well. Cook 2 minutes or until bubbly. Gradually add milk, stirring until well blended. Cook on medium heat until mixture boils and thickens, stirring constantly. Reduce heat to low; simmer 3 to 5 minutes or until thickened. Add 1-1/2 cups of the cheese; cook until melted, stirring constantly. Add macaroni; mix lightly.
SPOON into 1-1/2-quart casserole; sprinkle with remaining 1/2 cup cheese.
BAKE 20 minutes or until heated through.