01 -
Whip the butter, regular sugar, and brown sugar together until creamy and smooth. Add in the egg and vanilla, mixing until incorporated. Gently fold the flour, baking powder, baking soda, and salt into the mixture. Stir in the chocolate chunks and chill the dough in the fridge while you get the brownie layer ready.
02 -
Set your oven to 340°F (170°C) and line an 8x8-inch (20x20cm) baking dish with some baking paper. Melt the butter and chocolate together carefully, stirring it until silky smooth. In a different bowl, whisk the eggs, both sugars, and vanilla for about 3 minutes until thick and frothy. Combine the melted chocolate mixture into this bowl. Sift in the plain flour, cocoa, and salt, then fold it all together gently till it's mixed.
03 -
Pour out half the brownie batter into the baking dish and spread it out evenly. Drop spoonfuls of Nutella and pistachio cream randomly over this layer. Cover the filling with the remaining brownie batter, smoothing it gently over the top.
04 -
Scoop bits of the chilled cookie dough and place them across the top of the brownie batter, making sure it's evenly dotted around.
05 -
Pop it in the oven. If you want a slightly gooey center, bake it for around 28 minutes. Let it go for another 2-5 minutes if you want it firmer. The top should look golden and the edges will start pulling away from the pan.
06 -
Let it cool down in the pan. For really neat portions, put it in the fridge for an hour before slicing it up.