01 -
In a medium bowl, whisk together all-purpose flour, Dutch-processed cocoa powder, salt, baking powder, and cornstarch until evenly combined. Set aside.
02 -
Using a mixer on medium speed, beat the unsalted butter and brown sugar until light and fluffy, approximately 1 to 2 minutes.
03 -
Add the large egg and egg yolk to the creamed mixture and beat for 30 seconds, scraping down the bowl as needed.
04 -
Gradually add the dry mix to the wet ingredients, mixing on low speed until just combined to form a very thick dough.
05 -
Scoop 1 tablespoon of dough and roll into smooth balls. Roll each ball in granulated sugar and arrange them 2 inches apart on parchment-lined baking sheets.
06 -
Press the center of each dough ball with the back of a teaspoon to form an indentation. Freeze the trays for 10 minutes to firm up the dough.
07 -
Preheat oven to 350°F (177°C). Bake cookies for 10 to 11 minutes until edges are set but centers remain soft. Immediately deepen the indentations with a teaspoon after removing from the oven.
08 -
Allow cookies to cool completely on wire racks before filling.
09 -
Beat creamy peanut butter and softened unsalted butter until smooth and creamy, about 1 to 2 minutes. Add powdered sugar, vanilla extract, and salt, mixing on low until a thick, dough-like consistency forms.
10 -
Portion 2 teaspoons of peanut butter filling into each thumbprint. Wet fingertips and use them to press and smooth the filling evenly.
11 -
Combine semi-sweet chocolate chips and coconut oil in a microwave-safe bowl. Microwave at 50% power for 1 minute, stir, then microwave another 1 minute at 50% power until melted and smooth.
12 -
Drizzle melted chocolate over the peanut butter filling, coating each cookie aesthetically.