First, a good quality créme brûlée torch is essential and so worth having. You'll turn the torch on and hold it several inches from the sugared top of crème brûlée and slowly rotate the flame, keeping constant motion so it doesn't burn. Once the caramelized sugar is a lovely toffee color, turn torch off and let the dessert cool a bit so the caramelized sugar hardens into a crispy thin topping.