Place almonds in a heat-proof bowl and cover with boiling water. Let stand for a few minutes until cool enough to handle. Slip the almonds out of their skins one by one, leaving the remaining almonds in the warm water. Drain almonds in a colander.
Place almonds and confectioners’ sugar in the food processor fitted with a metal blade and process to a paste. Add cold water, 1/2 to 1 teaspoon at a time, if the paste is too dry. Scrape the sides a few times to ensure even processing. Add a few drops of almond extract towards the end of the process. Process marzipan until it is smooth and no longer grainy. Wrap in plastic wrap and store in a cool, dry place.