Add room temperature unsalted butter, cut into cubes, and granulated sugar into a stand mixer bowl or food processor.

Sift both flours in another large bowl.

Using the paddle attachment, start beating the butter at medium speed until nice and fluffy.

As soon as the dough starts clumping together, turn off the mixer, place it on the counter, and shape it into a ball.

Cover with cling film and refrigerate for a couple of hours.

Unwrap the cookie dough and place it on a work surface. Weigh pieces of dough of 10g each, roll them into small balls using the palms of your hands, and put them on two cookie sheets layered with parchment paper.

Place the tray in the freezer for 30 minutes.

Bake in a pre-heated oven at 350° for 10 to 12 minutes, rotating the tray midway, until slightly golden on the top.

Remove the cookies from the oven and let them cool for 5 minutes, then place them on a cooling rack.

Bake the second baking tray with the remaining cookies.

Place the chopped dark chocolate in a microwave-safe bowl and melt it in the microwave. Let the cool down until it becomes spreadable, then fill a piping bag.

Pipe a dollop of dark chocolate on the flat side of the cookie and top it with another half cookie, gently pressing it with your finger to spread the chocolate evenly.

Leave the cookies on a wire rack until the chocolate is completely set.

Enjoy with your favorite cup of tea or coffee! Buon Natale!