Preheat oven to 350°.
Cream together the butter, granulated sugar and brown sugar. Mix for 2 minutes.
Scrape the sides and add the egg and vanilla. Mix until just combined.
Stop the mixer and measure out the dry ingredients into the bowl. (The flour, black cocoa, soda and salt.)
In a separate bowl, measure out the peanut butter chips and chopped Oreos.
Start the mixer slowly, when the dry ingredients are about halfway incorporated, add in the Reese's chips and Oreo chunks.
Mix until *just* combined. Do not over mix. The mixture will be pretty dry.
Portion the dough out into 1/3 cup portions. Lightly pack the dough together, forming the dough into a flattened ball, similar to a hockey puck.
Repeat with remaining dough.
Bake at 350° for 12-14 minutes. The cookies will expand slightly and should no longer look wet and glossy in the middle when they come out of the oven.
Let the cookies sit on the pan for 20 minutes.
Add the white chocolate chips to a microwave safe bowl. Microwave the white chips for 30 seconds and then stir. Repeat microwaving and stirring until the white chocolate chips are melted smooth.
Transfer the melted chocolate chips into a small zip top bag. Snip the corner and drizzle on top of the cookies.
Serve warm.