Heat oven to 180 degrees Celsius.
Line a square 20cm x 20cm baking pan with baking paper and grease with spray and cook.
Place butter, sugar, cocoa and salt in a microwave safe bowl and microwave in 30 second intervals mixing after each one until everything is melted and the mixture feels warm to the touch.
Mix in eggs one at a time.
Fold in the flour until combined.
Fold in the chocolate chips.
Stir in the vanilla.
Pour in prepared pan and bake for 30 min until a toothpick inserted in the middle comes out almost clean with just a few crumbs.
Cool completely in pan on a wire rack.
For the fudge, place the condensed milk, chocolate and Nutella in a heatproof bowl of simmering water.
Stir until melted and smooth.
Spread evenly over brownie.
Chill in fridge until set and then cut into squares and enjoy!
