Grease and line a 20 x 20cm square pan with baking paper and pre-heat oven to 180ºC (160ºC fan forced).
In a medium size bowl, sift together plain flour, baking powder, cocoa powder and sugar. Add the eggs, melted butter and Nutella and gently mix together with a wooden spoon until well combined.
In another bowl, beat together the cream cheese, sugar, egg & vanilla on medium speed until smooth.
Pour the brownie batter into the prepared pan. Scoop cream cheese topping onto the brownie mixture, alternating with scoops of Nutella, then use a skewer to swirl the toppings into the batter.
Bake for 45-50 minutes until the top edges are firm to touch and the middle still slightly wobbly. A skewer inserted into the middle should come out with a few moist crumbs.
Remove brownie from the oven and allow to cool in the pan. Once cooled, slice into squares with a sharp knife.