As a confectionery expert with extensive knowledge in the field of sweets and desserts, I can tell you that the type of chocolate that hardens is typically dark chocolate. Dark chocolate has a higher percentage of cocoa solids, which contributes to its firmer texture when it cools and hardens. When chocolate is made, it goes through a process called tempering, which is essential for developing the right crystalline structure that gives chocolate its characteristic shine and snap. Proper tempering leads to a hard, glossy finish and a crisp break when you bite into it.

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There is not much of a secret or trick to dipping something in chocolate and getting it to harden, actually. Simply melt semisweet chocolate by itself or with a little cream or butter. Dip, then refrigerate. When the chocolate is cooled, it hardens.read more >>