Begin by creaming the softened butter in a large mixing bowl until light and fluffy, about 2-3 minutes. Gradually add powdered sugar, mixing until well incorporated. Then, add the egg yolk and continue to mix until smooth.

Slowly sift in the all-purpose flour into the butter mixture, combining with a spatula until just incorporated. Form it into a ball, wrap in plastic wrap, and refrigerate for about 30 minutes.

On a lightly floured surface, roll out the chilled dough to about ¼ inch thick. Cut into desired shapes using cookie cutters and transfer to a baking sheet lined with parchment paper.

Preheat your oven to 350°F (175°C). Bake the cookies for 10-12 minutes until the bottoms are lightly golden.

Allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely.

Choose your favorite filling and spread it on the flat side of one cookie. Place another cookie on top and press gently to sandwich together. Repeat with remaining cookies.

Chill the filled cookies in the refrigerator for 15-20 minutes to set the filling. Melt the chocolate and dip the tops of each cookie, allowing excess to drip off.

For added elegance, sprinkle freeze-dried fruit or edible gold leaf on the chocolate before it hardens. Allow decorated cookies to cool completely before serving.