If you don't have a blowtorch or a hot iron handy, you can caramelize the crema catalana in the oven. Put it under the broiler (the hottest possible top heat) until you see the sugar melting and crystalizing. Make sure your dish is oven safe for high temperatures and keep a close eye on it -- it can burn in an instant! It might not get as caramelized as the other methods, but it will definitely work.