Make the chocolate ganache. Chop the chocolate or pour the chocolate In a heatproof bowl. Heat the heavy whipping cream in a saucepan until barely simmering, about 2-3 minutes. Pour the warm heavy cream over the chocolate to melt. Stir the mixture until it is fully melted. Let the chocolate cool. It will thicken as it cools.
When the ganache is cool, use a cookie dough scoop to scoop the ganache into round balls. Place the balls in the freezer and freeze for 1 hour or overnight if possible.
While the ganache balls are chilling, make the cookie dough. In a medium-sized bowl, mix the flour, cocoa powder, baking powder, and salt. Set to the side.
In a large bowl with a hand mixer or in a stand mixer with a paddle attachment, cream the butter and the sugars until light and fluffy, about 2-3 minutes. Add in the egg and egg yolk, followed by the vanilla.
Add the dry ingredients to the butter mixture, scraping down the bowl as needed. Mix until fully combined.
Preheat the oven to 350 and take the ganache balls out of the oven.
Scoop the cookie dough the make the cookies. Scoop two cookie dough balls separately and then flatten them into discs. Use the two discs to surround the balls of the ganache. Make sure the balls of the ganache are fully covered with the dough. If any of it is peaking out, it will run out of the sides.
Bake the cookies in the oven for 9-11 minutes. The edges of the cookies will be firm when ready.
Let the cookies cool on the pan and enjoy while still warm.
