Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

In a medium bowl, whisk together the flour, cocoa powder, salt, and baking powder until combined.

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

Add the egg yolks and vanilla to the mixture, and beat on low speed until fully combined.

Slowly add the dry mixture into the wet ingredients in three additions, mixing until just combined.

Portion out the dough into 34 equal pieces and roll each into balls. Press a spoon gently into the center of each ball.

Cover with plastic wrap and refrigerate the dough for at least 1 hour.

Bake the cookies for 9-11 minutes until edges are set and centers are soft.

Re-indent the cookies after a few minutes and let them cool on the baking sheets.

Heat the cream until boiling, then pour it over the chocolate chips and stir until smooth.

Spoon the ganache into the indents of each cookie and allow it to set before serving.