Butternut Squash Au Gratin

HEAT oven to 350ºF. CUT squash lengthwise in half; discard seeds. Cut each half crosswise into 2 or 3 large slices; remove peel; then slice further into thin slices. Place slices in large saucepan. Add enough water to cover squash. Bring to boil on high heat; simmer on medium-low heat 8 to 10 min. or until squash is tender. MEANWHILE, cook bacon in skillet until crisp, stirring occasionally. Remove bacon from skillet with slotted spoon, reserving 1 Tbsp. drippings in skillet. Drain bacon on paper towels. Add onions to reserved drippings; cook and stir 5 min. or until crisp-tender. Stir in flour and pepper; cook and stir 1 min. Gradually stir in broth; cook and stir 2 to 3 min. or until thickened. Remove from heat. Stir in 1 cup cheese. DRAIN squash. Arrange half in 8- or 9-inch square baking dish; cover with half the sauce. Repeat layers; top with bacon and remaining cheese. BAKE 25 to 30 min. or until squash mixture is heated through and cheese is melted.