Almond paste is a firm paste made of blanched almonds and sugar finely ground between heavy-duty rollers. Commonly used in cake batters and pastry fillings, it's also the base ingredient in marzipan (which is made by adding hot sugar syrup and light corn syrup to almond paste). Its flavor marries perfectly with the sweetness of pears, peaches, and apricots, and is also delicious with chocolate.
You'll find cans or tubes of almond paste in most grocery stores.
Unopened almond paste will keep for a year or more in a cool, dry place.