01 -
Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper or a nonstick baking mat.
02 -
In a medium bowl, whisk together the flour, cocoa powder, salt, and baking powder until well combined.
03 -
In a large bowl, beat the softened butter, light brown sugar, and granulated sugar on medium speed until light and fluffy, about 2–3 minutes.
04 -
Add egg yolks and vanilla bean paste or extract to the butter mixture. Mix until thoroughly combined.
05 -
Gradually add the dry ingredients to the wet mixture on low speed. Mix until a smooth dough forms.
06 -
Scoop dough into 1-inch balls and place on prepared baking sheet, spacing about 2 inches apart. Gently press your thumb into the center of each ball to form an indentation.
07 -
Bake for 10–12 minutes until just set. Remove from oven and gently repress the indentation if needed. Allow to cool completely on the baking sheet.
08 -
In a small saucepan, heat the heavy whipping cream until it just begins to simmer. Remove from heat and pour over the chocolate chips in a heatproof bowl. Let stand 2 minutes, then stir until smooth and glossy.
09 -
Spoon the chocolate filling into each cooled cookie indentation. Sprinkle with nonpareils if desired. Allow filling to set before serving.