Preheat oven to 400 degrees. Remove the steams and outermost leaves from the brussel sprouts and cut them into halves or quarters depending on the size of sprouts. Cook bacon until crisp and crumble into bits. Place brussel sprouts and bacon crumbles on a piece of aluminum foil. Drizzle with the balsamic vinegar and season with salt and pepper. Fold foil into a pouch, pinch sides to seal. Place pouch on baking sheet and roast in oven for 1 hour, drizzle with more balsamic and serve.