PREHEAT oven to 350°F. Cook bacon in skillet on medium heat until crisp; drain, reserving 2 Tbsp. of the drippings in skillet. Crumble bacon; set aside. Add onion to reserved drippings; cook and stir on medium-high heat until lightly browned. Drain.
MIX all ingredients in 1-1/2-qt. casserole dish; cover.
BAKE 1 hour or until heated through.