In a medium bowl mix the dry ingredients: flour, baking powder, baking soda and salt. Set aside.
In a large bowl whisk unsalted butter (softened to room temperature), granulated white sugar and brown sugar together until creamy and smooth, about 1-2 minutes. Add the egg and mix until combined. Scrape the sides of the bowl as needed. Add creamy peanut butter and vanilla extract and whisk on high speed until combined.
Add the dry ingredients to the wet ingredients and mix until combined.
Cover with plastic wrap and chill for at least 1 hour, for up to 3 days. If you're chilling it for longer, the dough will become hard to work with, so let it sit for 30 minutes at room temperature.
Preheat the oven to 180°C and line 2-3 baking sheets with parchment paper.
Roll about 1.5 tbsp dough into balls per cookie, then roll the balls in granulated white sugar if desired. Place on baking sheets and make a criss cross pattern using a fork on every cookie. Bake for 10-12 minutes or until slightly brown on the edges. The centers will be very soft, but they will firm up as they cool.
Remove from the oven. Cool for 5 minutes on the baking sheet, then transfer on a cooling rack to cool completely.
Melt chocolate chips in a microwave safe bowl, 30 seconds at a time, whisking every time, until smooth and completely melted. Dip the cooled peanut butter cookies, return to the baking sheets. Chill in the refrigerator for 30 minutes or until the chocolate is set.