01 -
Mix peanut butter, softened butter, white sugar, and brown sugar in a big bowl with a mixer for 3-4 minutes until fluffy. Add vanilla and part of a beaten egg, stirring until smooth. Blend the dry ingredients (flour, salt, and baking soda) in another bowl, then gently mix these into the wet ingredients. Don’t overdo it. Set aside.
02 -
In a mixing bowl, whisk melted butter and sugar together for a minute or so. Stir in the vanilla and egg. Sift cocoa powder, flour, salt, and baking powder into the wet base, and gently fold it all together until the dough looks smooth.
03 -
Set your oven to 350°F (175°C) and cover a baking tray with parchment. Scoop equal amounts of brownie and peanut butter dough (about a tablespoon each), gently roll them together, and twist to make a marble look. Don’t overly blend them—keep those swirls noticeable.
04 -
Place the dough swirls on the tray, with some space (at least an inch or two apart) between each one. Bake for around 10-12 minutes. The edges should look set, but the middle should still be soft.
05 -
Leave the cookies to cool directly on the tray for about 5 minutes. Then, move them onto a cooling rack to fully set before you take a bite.