Step 1

Preheat oven to 350°.

Step 2

In a small bowl, mix the flour, cocoa powder, baking soda and salt together.

Step 3

In another bowl, beat the butter and sugars together for 2-3 minutes. Add the egg yolk and mix well. Add the flour mixture to the butter mixture and mix just until combined.

Step 4

Use a cookie scoop to scoop tablespoon sized balls and roll them between your hands into perfect ball shapes before placing on a parchment lined cookie sheet.

Step 5

Bake for 10 minutes. Remove from oven and use your thumb (or the back of a teaspoon) to make a thumb-sized indention in the center of each cookie while still warm. If the cookies break or fall apart, you can kind of push them back together. Bake for 3 more minutes and then let them cool completely.

Step 6

While the cookies are cooling, you can make the ganache. Place the chopped chocolate in a bowl. Warm the cream in a saucepan over medium heat for a few minutes and then as soon as it starts to barely bubble around the edge, remove from heat and pour over the chocolate. Whisk until smooth. Let cool for about 5-10 minutes. Use a small spoon to scoop the ganache into each indention on the cookies. Allow about an hour for the ganache to set before serving.