In a medium mixing bowl, whisk together 1 ½ cups of all-purpose flour, ½ cup of Dutch process cocoa powder, ¼ teaspoon of salt, and ½ teaspoon of baking powder until combined. Set aside.

In a large mixing bowl, beat ½ cup of unsalted butter with ¼ cup of light brown sugar and ¼ cup of granulated white sugar for about 2 minutes until light and fluffy.

Add 2 room-temperature egg yolks and 1 teaspoon of vanilla to the butter-sugar mixture and mix on low speed until well combined.

Gradually add the dry mixture to the wet ingredients, mixing on low speed until just combined, avoiding over-mixing.

Portion the dough into 34 equal balls, press down the center of each, and refrigerate for 1 hour.

Preheat oven to 350°F (175°C) and bake the cookies for 9-11 minutes until edges are set.

Repress the centers of the cookies with a measuring spoon immediately after baking to deepen the indents.

Cool the cookies on a baking sheet for about 5 minutes before transferring to a wire rack.

Heat ½ cup of heavy whipping cream in a saucepan, pour over 1 cup of chocolate chips, stir until smooth.

Once cooled, fill each cookie indent with ganache and allow to set in the refrigerator for 10-15 minutes.