Step 1

In a medium mixing bowl, whisk together the flour, powdered sugar and salt. Set aside.

Step 2

In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter, cream cheese, lemon zest and vanilla extract until smooth, 20 to 30 seconds. Add the egg white and beat to combine. Add the flour mixture and mix just until a dough forms. Turn out onto a piece of plastic wrap, press and form into a square-shape and wrap tightly. Refrigerate until firm, at least 1 hour.

Step 3

Preheat the oven to 375 degrees F. Line 2 baking sheets with parchment paper.

Step 4

In a small bowl, beat the egg yolk with a splash of water for the egg wash. Set aside.

Step 5

Dust a clean work surface with flour. Working with half of the dough at a time, roll out the dough to 1/8 inch thick. Trim the edges and cut into 3-inch squares. You can reroll the dough once. Lay the squares on the sheet tray then dollop 1 teaspoon of cherry jam in the center of each. Fold one corner into the center, brush the corner with the egg wash, then fold the opposite corner into the center overlapping the other corner of dough. Press to seal. Repeat with all of the cookies, then bake until puffed up and golden, begin checking at 13 minutes. Cool on the pans for about 1 hour, then dust with powdered sugar. Keep in an airtight container on the counter for up to 3 days.