Preheat oven to 350F.

Place flour, sugar, butter, and salt in the bowl of a food processor; process until the texture resembles coarse crumbs.

In a small bowl, whisk together egg yolks and vanilla; add to the processor with the motor running. Process until the dough forms into a ball.

Fill your cookie press ¾ of the way full (do not chill the dough!) and form cookies on cool, ungreased baking sheets according to manufacturer’s instructions.

Use a pastry brush to brush the cookies with the egg wash and decorate with sprinkles as desired. Bake for 10 - 15 minutes until the cookies are firm but not brown. Cool completely on a wire rack.