Melting Chocolate

This might sound like a simple matter of heating, but there is a fascinating science to it. When chocolate melts, the cocoa-butter crystals start to break down and disappear. To keep its stability in the cookie so it holds shape without melting at the touch, looks glossy when dry, and “snaps” when you bite into it, it needs to be brought back to temper a stage where the crystals have reformed. The easiest method: Drop a few chunks of already tempered chocolate of the same kind (the packaged stuff that is still glossy and unblemished) into the melted batch and stir until incorporated. The stable crystals in the chocolate chunks will slowly spread throughout the bowl, making the rest of the chocolate ready to use.