Pop that bowl in the microwave and on “High” setting, microwave for about 15 minutes. Disclaimer: every microwave is a tad different in power – mine is a cheap machine and isn’t very powerful, so I microwave it for 20 minutes. The longer you microwave it, the firmer the caramels will be. You might microwave for 12 minutes to start, give it a stir and a peek, (or try the ice water test to see how firm it sets) and give it more time if you need to.