1. Add the butter and sugar for the dough to a large bowl and mix until light and fluffy. Add the egg and vanilla extract and mix in well. Combine the flour, cocoa, baking powder, and salt and add to the bowl. Mix/knead until just combined. Wrap the dough in plastic wrap and place in the fridge for at least 2 hours (or overnight).

2. Preheat the oven to 325°F (165°C). Line a baking sheet with baking parchment and set aside. Use half of the dough (keep the rest in the fridge) and roll it out on a floured surface. Cut out as many ghosts as possible using a ghost cookie cutter*. Collect dough scraps and roll them out again cut out more ghosts. Place the dough pieces on the baking sheet, spacing them slightly apart, and bake the first batch of cookies for about 10-11 minutes. Remove from oven and let cool down on the baking sheet for some time, then transfer to a wire rack and let cool down completely. Repeat with the remaining dough until all has been used – you want an even number of cookies.

3. For the glaze, mix the confectioners’ sugar with vanilla extract and a little bit of milk. You want a mixture that is quite thick. Add more confectioners’ sugar or more milk to adjust to get the right consistency. Glaze half of the cookies and let dry for at least 8 hours, preferably overnight. Cover the leftover glaze as airtight as possible and place in the fridge. When the glaze on the cookies has dried nicely, color the leftover glaze with some black food coloring and draw faces onto the cookies. Let dry for another 2-3 hours.

4. Add the peanut butter, butter, confectioners’ sugar, and vanilla extract for the filling to a bowl and mix until you got a light and smooth cream. Fill into a piping bag with a round piping tip. Pipe a thick border of cream on the cookies without decorations and fill the empty centers with jam. Top these cookies with the decorated cookies to create sandwiches. If you like, you can additionally press the sandwich cookies at the edges into colored sugar pearls to make them more colorful.