Preheat oven to 375° F. Slice sprouts in half and place in a bowl with olive oil, garlic, salt and pepper and toss until coated well. Spray cookie sheet with a non-stick spray and place Brussels Sprouts evenly on sheet. Bake for 25 minutes, turning sprouts halfway through baking.
Options: Add onion slices before roasting or toss with freshly crumbled bacon after roasting.