Gluten-Free Dulce de Leche Sandwich Cookies

Preheat your oven to 350 degrees Fahrenheit (175 degrees Celsius). To prevent the baking sheets from sticking, line them with parchment paper.

In a bowl, combine cornstarch, flour, baking powder, and baking soda. Whisk these dry ingredients together until they are well incorporated.

In a large bowl, use an electric mixer to cream butter and sugar until the mixture is light and fluffy. Then, whisk in egg yolks one at a time, followed by the addition of lemon zest and vanilla extract with the last yolk.

Mix the flour mixture into the butter mixture using a spoon, until the dough comes together and forms a cohesive ball. Wrap the dough in plastic wrap and refrigerate for 30 minutes to 1 hour.

Roll out the chilled dough to a thickness of about 1/4 inch. Use a small round cookie cutter to cut out the desired shapes, and place them on the prepared baking sheets.

Bake the cookies in a preheated oven until they are set but not browned, taking 7 to 10 minutes. Remove the cookies from the oven immediately and let them cool on a wire rack.

For an added layer of flavor, spread the underside of 1 cookie with 1 teaspoon dulce de leche. Sandwich together with another cookie, pressing gently until the filling comes out on the sides. Roll in shredded coconut to coat. Repeat with remaining cookies, dulce de leche, and coconut.