1. Make the chocolate dough: Cream butter with granulated and brown sugar until fluffy. Mix in egg and vanilla. Stir in flour, cocoa, baking soda, salt, and espresso powder (if using) until combined.

2. Make the pink dough: Cream butter with granulated and brown sugar until fluffy. Mix in egg and vanilla. Stir in flour, baking soda, salt, and raspberry powder or food coloring until evenly colored.

3. Chill both doughs for 30 minutes.

4. Preheat oven to 350°F (177°C) and line baking sheets with parchment paper.

5. Scoop dough into balls (about 1½ tablespoons each). Place on baking sheet and press a well into the center of each ball with your thumb or the back of a spoon.

6. Bake for 10–12 minutes, until edges are set but centers are still soft.

7. Immediately re-press the centers (they will puff slightly) to keep the wells deep. Cool on the baking sheet for 10 minutes, then transfer to a rack to cool completely.

8. Make the ganache: Heat heavy cream until steaming (not boiling). Pour over chopped chocolate (and butter if using). Let sit 1 minute, then stir until smooth and glossy.

9. Fill each cooled cookie center with ganache. Add toppings (sprinkles, raspberries, chocolate squares, drizzle) if desired.

10. Let ganache set at room temperature, or chill 10–15 minutes for a quicker set before serving.