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

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

Gently mix in egg yolks and vanilla extract into the butter and sugar mixture until fully blended.

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

Scoop out dough, roll into balls, and place on a baking sheet. Press down in the center to create indents.

Chill the shaped dough in the refrigerator for 1 hour.

Preheat oven to 350°F (175°C) and bake cookies for 9 to 11 minutes until edges look firm.

Prepare the ganache by boiling heavy cream and pouring it over chopped chocolate; stir until smooth and mix in cherry preserves.

Fill each thumbprint indentation with ganache and let cool before serving.