1. Preheat oven to 375°F (190°C). Line baking sheets with parchment paper.

2. In a large bowl, cream together 1 cup softened butter and granulated sugar until light and fluffy.

3. Beat in the egg and 1 teaspoon vanilla extract.

4. In a separate bowl, whisk together flour, cocoa powder, baking soda, and salt.

5. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

6. Roll dough into 1-inch balls and place on prepared baking sheets.

7. Bake for 8–10 minutes, or until set. Let cool completely on a wire rack.

8. Make the peanut butter filling: In a medium bowl, combine creamy peanut butter, powdered sugar, ¼ cup softened butter, and 1 teaspoon vanilla. Mix until smooth and creamy.

9. Spread a generous dollop of filling onto the flat side of half the cooled cookies; top with remaining cookies to form sandwiches.

10. Make ganache: Place dark chocolate chips in a heatproof bowl. Heat heavy cream until just simmering; pour over chips and let sit 5 minutes, then stir until smooth and glossy.

11. Dip the top half of each cookie sandwich into ganache to create a “hat” effect; place on parchment to set.

12. Optionally, add festive sprinkles or edible glitter before the ganache fully sets.