Step 2: Beat butter and brown sugar until light and fluffy.
Step 3: Add egg yolks and vanilla.
Step 4: Combine flour, cocoa powders, baking powder, and salt in a bowl and stir with a whisk. Add to butter mixture and beat until combined.
Step 5: Using a cookie scoop, place scooped cookie dough on parchment lined baking sheet. Chill for 40 minutes.
Step 6: Bake, remove from oven and cool completely.
Step 8: Beat butter.
Step 9: Add powdered sugar and vanilla.
Step 10: Add whipping cream.
Step 11: Frost cookies and top with sprinkles.
Step 12: Enjoy!!