Preheat the oven to 350 degrees F. Line several baking sheets with parchment paper and set aside.
For the Chocolate Dough:
Using an electric mixer, cream the butter and sugar together until fluffy and smooth, about 3-5 minutes. Scrape the bowl and add the egg and vanilla. Beat again until smooth.
In a separate bowl, mix together the flour, cocoa powder, baking powder, and salt. Slowly add the dry mixture into the butter mixture. Scrape the bowl and beat until just mixed through. Chill the dough until ready to use.
For the Peanut Butter Dough:
In a separate bowl, use an electric mixer to cream the butter, peanut butter, and both sugars together until fluffy and smooth, about 3-5 minutes. Scrape the bowl and add the egg and vanilla. Beat again until smooth. Add the flour, baking powder, and salt. Beat again until well combined.
Roll the peanut butter dough into 1 1/2 teaspoon balls. Portion out the chocolate dough into 2 – 2 1/2 teaspoon balls, just slightly larger than the peanut butter balls.
Press the chocolate balls flat with the palm of your hand. Place one peanut butter ball on top of each circle. Pinch up the sides of the circle until the filling is completely enclosed. Flip the balls over, so that the pinched sides are down. Dip the bottom of a drinking glass in sugar and gently press the balls down to 3/4-inch disks. Repeat with the rest.
Place on parchment paper lined cookie sheets, 2 1/2 inches apart. Bake for 12 minutes, until puffy. The centers should still look slightly undercooked. Then allow the cookies to cool on the baking sheets for 3-5 minutes before moving.
You can add food coloring to the peanut butter dough to enhance them for the holidays! Try green, orange and purple for Halloween, or red and green for Christmas.