Gather the ingredients.
Coarsely chop the almond paste into quarter-sized chunks and place in the bowl of a large stand mixer fitted with a paddle attachment.
Add powdered sugar to the bowl and mix on low speed until the mixture has a fine, sandy texture. If you don't have a stand mixer, feel free to use a food processor.
Pulse the almond paste and powdered sugar until the mixture resembles wet sand.
With the mixer on low speed, slowly add the egg whites (and almond extract, if using) until the mixture pulls away from the sides of the bowl and forms a ball. (If you are using a food processor, look for the same appearance.) You may not need to add all of the egg whites.
Dust a countertop or cutting board with powdered sugar and knead the marzipan until it develops a smooth, pliable texture. It should have no lumps or dry patches.
Use the marzipan immediately or store it for later use.
Enjoy it on your favorite cake or as a tasty, nutty snack.