Directions
To make the cookies: Preheat the over to 350ºF [180ºC]. Line two baking sheets with parchment paper.
In a small bowl, combine the flour, baking soda, baking powder, and salt. Set aside.
In a large bowl, with a hand mixer, beat together the butter, granulated sugar, and brown sugar until light and smooth, about 3 minutes. Stir in the peanut butter, egg, and vanilla. Gradually stir in the flour mixture until combined.
Roll pieces of dough into 1 in [2.5 cm] balls and place on the prepared baking sheets about 1 in [2.5 cm] apart.
Bake for 10 minutes, then remove from the oven. Using a small spoon, make a small indentation in the middle of each cookie. Return the cookies to the over for another 6 to 7 minutes, or until set. (After removing from the oven, you may need to use the spoon again to make the indentations clear.) Transfer the cookies to a wire rack to cool completely, 1 to 2 hours
To make the filling: Melt the chocolate, butter, and corn syrup together using a hot water bath or the microwave oven. Stir until completely melted and smooth. Remove the bowl from the water bath and set aside to cool slightly, 3 to 5 minutes
When the cookies are completely cool, use a spoon to fill each indentation with the chocolate filling. Set aside and let the chocolate filling cool and harden, 1 to 2 hours. (If your kitchen is warm, refrigerate the cookies so the filling can harden.) Store in an airtight container at room temperature for up to 1 week.
This recipe is courtesy of Amy Guittard from her Guittard Chocolate Cookbook.