Preheat the oven to 350°F and line two baking sheets with parchment paper.
In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt.
In a large bowl, cream together butter, brown sugar, and granulated sugar until fluffy.
Add egg yolks and vanilla, mixing until pale and fluffy.
Gradually add dry ingredients to the butter mixture, mixing until combined.
Scoop dough into portions, flatten, and place a frozen ganache ball in the center.
Close the dough around the ganache, roll into balls, and place on prepared baking sheets.
Bake for 10-11 minutes, then cool on wire racks.
Dust with powdered sugar and enjoy the gooey goodness!