11.In a medium bowl STIR together flour, cocoa powder, and baking soda: set aside.
2.In a large mixing bowl COMBINE butter,the 1/2 cup granulated sugar, brown sugar, and 1/4 cup of the peanut butter; BEAT with mixer until combined. ADD egg, milk, and vanilla; BEAT well. BEAT in as much flour mixture as you can with mixer. USING wooden spoon, STIR in any remaining flour mixture. SHAPE dough into 32 balls, each about 1 1/4 inches in diameter. SET aside.
23. For filling, in bowl COMBINE powdered sugar and remaining 1/2 cup peanut butter. With mixer BEAT until smooth; KNEAD by hand if necessary. SHAPE into 32 balls.
34. PREHEAT oven to 350 degrees F. On work surface, FLATTEN a chocolate dough ball; TOP with peanut butter ball. SHAPE flattened dough over peanut butter ball, COMPLETELY covering peanut butter ball; RESHAPE into ball. REPEAT with remaining balls.
45. PLACE balls 2 inches apart on cookie sheet. FLATTEN with bottom of glass dipped in the 2 tablespoons granulated sugar. BAKE about 8 minutes. Let STAND 1 minute. Transfer to racks; Cool. Makes 32 cookies