To finely crush soft peppermint candies, place in a medium resealable plastic bag. Using a rolling pin, crush candies; continue to roll over candies in bag with rolling pin until finely crushed (peppermint pieces no larger than ⅛ inch thick).
Peppermint Pastry Cream can be made through step 3 up to 4 days in advance and kept refrigerated. Stir in finely crushed peppermint candies just before ready to use.