Pre-heat the oven to 170ºC and grease and line a 27cm x 17cm baking tray.
Melt 100g of the white chocolate with the butter, stirring to combine. Set aside.
Beat the Tatua Mascarpone, brown sugar, vanilla extract and eggs together until smooth.
Mix in the melted white chocolate and butter.
In a large bowl whisk the ground almonds, baking powder and salt together. Add the white chocolate mascarpone mix and stir until combined. Add the remaining chopped white chocolate bits.
Pour into the tray and bake for 30 mins. Cool in the tin then chill in the fridge before cutting into slices. Blondie is best stored in the fridge.