Magic in the middle cookies

1 1/2 cups all-purpose flour
1/2 cup unsweetened cocoa
1/2 tsp. baking soda
1/4 tsp. salt
1/2 cup granulated sugar (plus more for dipping)
1/2 cup firmly packed brown sugar
1/2 cup unsalted butter, softened
1 cup creamy peanut butter, divided
1 tsp. vanilla extract
1 large egg
3/4 cup powdered sugar
Preheat oven to 375°. Whisk together first 4 ingredients in a medium-size mixing bowl. In a separate bowl, beat together granulated and brown sugars, butter, and 1/4 cup peanut butter until light and fluffy. Add vanilla and egg, beating to combine. Stir in dry ingredients, blending well. Set dough aside. Stir together remaining 3/4 cup peanut butter and powdered sugar until smooth. With floured hands, roll mixture into 26 (1-inch) balls. Break off about 1 Tbls. cookie dough; make an indentation in center with thumb, and press 1 peanut butter ball into indentation. Wrap dough up and over filling, pressing to seal; roll cookie to smooth it out. Repeat for each cookie. Dip top of each cookie in granulated sugar, and place 2 inches apart on lightly greased baking sheets. Use greased bottom of drinking glass to flatten each cookie to about 1/2 inch thick. Bake cookies at 375° for 7 to 9 minutes or until set. Let cool on wire rack.