Preheat your oven to 350°F (175°C) and line a cookie sheet with parchment paper.
In a stand mixer’s bowl, combine the butter, peanut butter, sugar, and brown sugar until creamy and smooth.
Add vanilla and egg, mixing well.
In a separate bowl, whisk together the flour, salt, and baking soda.
Gradually add the dry ingredients to the mixer, blending until a smooth dough forms.
Roll the dough into tablespoon-sized balls, roll each in extra sugar, and place on the prepared sheet.
Bake for 10 minutes, or until the cookies are golden brown and begin to crack.
Remove from oven and gently press down the center of each cookie with the bottom of a flat glass.
Let cookies cool on the sheet for 5 minutes before transferring to a wire rack to cool completely.
Melt the chocolate chips in a microwave-safe bowl in 15-second intervals, stirring between each, until smooth.
Spoon the melted chocolate into the center of each cookie and allow to set for about an hour.
Sprinkle powdered sugar over the cookies before serving.