Combine the unsalted butter, seeds of the vanilla bean, sugars and oil, beat until lightly aerated. Do not discard the vanilla bean – this can be stored in a jar with sugar, and added to over time to create a beautiful vanilla sugar.
Add the eggs one at a time and mix until combined.
Whisk together the flour and Double Dutch Cocoa together, then add the salt. Gently stir the flour mix through the butter until combined. Add the chocolate and fold through.
Line a small baking tray with baking paper, carefully spread the brownie mix evenly over the base.
Using a teaspoon, place 8 chunks of the nut butter in even spaces over the top of the mix. Then using the tip of a knife, or a skewer, gently swirl the nut butter into the brownie.
Bake at 180°C for 20 minutes. Once baked, the brownie should not have any wobble left to it, but if using a skewer test, it should still have some wet mix on it.
