Preheat oven to 400 degrees. Combine brown sugar and butter and heat on the stove until melted. The microwave will work as well. Grab a large bowl and place the Brussel sprouts in it. Cover the Brussel sprouts with the brown sugar mixture. Spread the mixture evenly on a cookie sheet. Sprinkle with the pecans. Bake for about 20-30 minutes, or until desired doneness. I like mine a bit crunchy. Serve hot.