Espresso Walnut Marzipan Cookies

To prepare marzipan: Pulse walnuts in a food processor until ground. Add 1/2 cup confectioners' sugar; process until walnuts are finely ground. Add vanilla; pulse again a few times. Add water, 1 teaspoon at a time, pulsing until a cohesive dough forms. Remove the dough from the food processor and shape into a log about 7 inches long. Wrap in parchment paper and refrigerate for 1 hour or up to 1 day.

To prepare cookie dough: Preheat oven to 350°F. Line a baking sheet with parchment paper.

Place the chilled marzipan and butter in a food processor or medium bowl. Process or beat with an electric mixer until well combined, scraping sides as needed. Add granulated sugar and process or beat, scraping the sides as needed, until combined. Add espresso mixture and pulse or beat until combined, scraping the sides as needed.

Whisk all-purpose flour, pastry flour and cornstarch together in a medium bowl. Add to the marzipan mixture, 1/4 cup at a time; pulse or beat until combined.

Roll the dough into 1-inch balls and arrange about 2 inches apart on the prepared pan. Bake until lightly puffed and crackled, 10 to 15 minutes. Cool on the pan for 5 minutes, then transfer the cookies to a wire rack to cool completely, about 10 minutes.

To prepare espresso glaze: Whisk espresso powder and warm water in a medium bowl until dissolved. Add confectioners' sugar and whisk until smooth. Add almond milk, 1 tablespoon at a time, whisking until the glaze is smooth and glossy. 

Dip the cooled cookies in the glaze. Return the cookies to the rack and sprinkle with lemon zest. Let the glaze set completely.