Preheat your oven to 350°F (175°C).

In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.

Add the eggs, one at a time, mixing well after each addition. Then stir in the vanilla extract.

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

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

Scoop tablespoon-sized portions of the dough and place them on a parchment-lined baking sheet.

Make an indentation in the center of each cookie with your thumb or the back of a spoon.

Fill each indentation with your desired filling.

Bake in the preheated oven for 12-15 minutes, or until the edges are set.

Let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.