Start by prepping your 8x8-inch pan. Lightly grease it with butter and line it with parchment paper, leaving some overhang.

Spoon the Nutella into the pan and spread it evenly. let it freeze for about an hour, until it’s nice and firm. Once solid, lift it out and place it on a plate, then pop it back into the freezer so it stays chilled while you prep the batter.

While that’s freezing, preheat your oven to 180°C (350°F). Re-line the same pan with a new sheet of parchment paper.

In a heatproof bowl, melt the butter and dark chocolate together in 30-second microwave bursts, stirring in between. Once smooth and glossy, let it cool for a couple of minutes.

Mix in the eggs, brown sugar, and vanilla, then sift the flour, cocoa, and salt. Blend until everything is incorporated, even if a few lumps remain.

Pour half of the brownie batter into your pan and smooth it out. Place the frozen Nutella slab carefully on top, then layer the rest of the batter over it and gently spread to cover.

Bake for around 35 minutes. Once the skewer comes out with a touch of Nutella and some damp crumbs, they’re done. 

Cool the brownies in the pan for 20 minutes, then transfer them out to finish cooling completely before slicing. Enjoy!