Frangipane is a sweet almond-flavored custard used in a variety of ways including cakes and such pastries as the almond croissant, Bakewell tart, conversation tart, Jésuite and pithivier.
A French spelling from a 1674 cookbook is franchipane with the earliest modern spelling coming from a 1732 confectioners' dictionary. Originally designated as a custard tart flavored by almonds or pistachios it came later to designate a filling that could be used in a variety of confections and baked goods.
It is traditionally made by combining two parts of almond cream (crème d’amande) with one part pastry cream (crème pâtissière). Almond cream is made from butter, sugar, eggs, almond meal, bread flour, and rum; and pastry cream is made from whole milk, vanilla bean, cornstarch, sugar, egg yolks or whole eggs, and butter. There are many variations on both of these creams as well as on the proportion of almond cream to pastry cream in frangipane.