HEAT oven to 375°F.
COOK vegetables in boiling water in large saucepan 8 to 10 min. or until tender. Meanwhile, melt butter in medium saucepan on medium heat. Add flour and seasonings; mix well. Cook and stir 1 min. Gradually stir in milk until well blended. Bring to boil on medium heat; cook 5 min. or until thickened, stirring constantly. Stir in cheese; cook on low heat 1 min. or until melted, stirring constantly.
DRAIN vegetable mixture; spoon half into 13x9-inch baking dish sprayed with cooking spray. Cover with half the cheese sauce. Repeat layers; cover.
BAKE 45 min. to 1 hour or until vegetable mixture is heated through, uncovering after 30 min.