Step 1 Heat the oven to 350 degrees.
Step 2 Grind the bitter almonds, if using, with the regular almonds in a food processor. Otherwise, just grind the regular almonds.
Step 3Cream together the butter and sugar in the bowl of an electric mixer. Add the almond extract, if using. Mix together the flour and ground nuts, and slowly add to the butter mixture to form a dough. The dough will be crumbly.
Step 4Shape the dough, about a teaspoon at a time, into balls and place on an ungreased baking sheet. Lightly flatten the cookies. Bake until lightly browned, 15 to 18 minutes. Roll the cookies in the powdered sugar while still warm. Repeat until all the dough is used.