1/2 c. chopped onions
1/2 c. catsup
1 tbsp. brown mustard
1/4 c. firmly packed brown sugar
2 (16 oz.) cans baked beans

Combine onion, catsup, mustard and brown sugar in a deep 2 quart casserole. Heat, uncovered, in microwave oven for 4 minutes. Add beans; stir thoroughly to combine. Heat, covered, in microwave for 12 to 15 minutes or until beans are hot.