Peanut butter thumbprint cookies with dark chocolate

Flour, all-purpose	1 ¼ cups
Baking soda	¾ teaspoon
Baking powder	½ teaspoon
Salt	¼ teaspoon
Butter, unsalted, room temperature	½ cup + 2 tablespoons
Sugar, granulated	½ cup
Sugar, dark brown	½ cup firmly packed
Peanut butter, crunch	½ cup
Egg, lightly beaten	1 large
Vanilla extract	1 teaspoon
Chocolate, dark, broken into pieces	2 ounces
Corn syrup, light	¾ teaspoon

1. Preheat the oven to 350°F; line two baking sheets with parchment paper. 
2. In a small bowl, combine the flour, baking soda, baking powder, and salt; set aside. 
3. In a large bowl, with a handheld mixer, cream the butter and sugars together until light and fluffy, about 3 minutes. 
4. Stir in the peanut butter, egg, and vanilla. 
5. Gradually stir in the flour mixture until combined. 
6. Roll pieces of the dough into 1-inch balls, and place on the baking sheets about 1 inch apart. 
7. Bake for 10 minutes, and then remove from the oven. 
8. Using a small spoon, make a small indention into the middle of each cookie. 
9. Return the cookies to the oven for another 6 to 7 minutes, or until set. 
10. Transfer the cookies to a wire rack to cool completely, about 1 to 2 hours. 
11. Melt the chocolate, butter, and corn syrup together using a hot water bath; stir until completely melted and smooth. 
12. Remove the bowl from the water and let cool slightly, about 5 minutes. 
13. When the cookies are completely cooled, use a spoon to fill each indention with the chocolate filling. 
14. Set aside and let the chocolate cool and harden, 1 to 2 hours. 

Recipe mildly adapted from Guittard Chocolate Cookbook