You’ll need to do this first step and then refrigerate for at least half an hour before making the rest of the cookie dough. Place half a cup of the chopped white chocolate into a microwave proof bowl with the peanut butter. Microwave in 30 second increments, stirring after each one until the white chocolate is completely melted. This should take around 2-3 minutes. Be careful not to burn the chocolate!
Pour the chocolate mixture into a shallow baking tray (with sides), or dish, or container or anything where you’ll be able to pour the chocolate in and get a nice thin layer. Pour the chocolate in and smooth the top if necessary, it should only be about 2cm or 3/4in thick. Cover with a lid or plastic wrap and put in the fridge to chill for between 30 mins - 2 hours. Once chilled, break the chocolate into pieces about the size of your thumb and store in a ziplock bag (if you’re not using it all, or right away).
Place the butter and the sugars either in the bowl of a stand mixer or in a large bowl and use an electric hand beater. Beat the butter and the sugar on a high speed until creamed, pale and fluffy.
Add the eggs, one at a time, and beat until combined after each addition. Then add the vanilla and beat on a medium speed until everything is combined.
Add the flour, black cocoa powder, baking powder, salt and baking soda to the butter mixture. Mix on a low speed until all the dry ingredients are nearly combined and there are streaks of flour remaining. Then add the white chocolate, the ‘peanut butter’ chocolate and the dark chocolate to the mixture. Mix everything until combined, if needed you can mix the chocolate in by hand to ensure that it’s evenly distributed throughout the dough.
Now everyone’s favourite step... You’re going to need to refrigerate the dough for at least 1-2 hours before rolling/scooping and baking. You can leave it up to 48hrs at this stage if you cover the bowl tightly in the fridge.
Once the dough has chilled, leave it on the counter whilst you prepare everything to let it warm up a little bit. Preheat the oven to 180C and grease (if needed) and line 3-4 baking sheets/trays with either baking paper or silicone baking mats. Depending on the size of your oven, you’ll need to do 3-4 rounds of trays of dough as you’ll need to space them out.
For this step, you can either use a cookie scoop, a tablespoon or your hands. You want about 2 Tbspn of dough for small cookies and 4 Tbspn of dough for large cookies. The ones in the photos are small cookies. If you’re using a cookie scoop, just scoop the dough and place around 5cm (2in) apart on your trays. There should be 9-12 balls on large trays and 6 on small trays. If you’re using a tablespoon or your hands, get a rough 2 Tbspn of dough in your hands and quickly roll into a ball and place on the tray.
Bake each tray of cookies between 10-11 minutes, definitely no longer than 11 minutes! The cookies should be set and look just crisped and baked on the outside but it’s fine if they’re still a little jiggly, they’ll set more after they’ve come out of the oven.
Cool the trays on a wire rack for about 10 minutes, then slide the cookies onto the wire rack to cool completely. Time to enjoy!! Yum! The cookies will keep for up to a week in an airtight container on the counter.