In a bowl over a pan of simmering water melt together the butter and dark chocolate.
In a seperate bowl whisk together the eggs and the caster sugar until light and fluffy.
Pour the melted chocolate mixture into the egg mixture slowly and continue to whisk until it all comes together.
Sieve in the baking powder, plain flour, sea salt and cocoa powder. Fold this through the mixture until it is all combined together.
Line a 7 inch square baking tin with parchment paper. Pour a third of the batter in the bottom of the tin and spread it to the corners with a spatula.
Slightly heat up both spreads in the microwave for 20-30 secend so they are easy to spread. Make sure you remove any foil from the top.
Spread the Dairy Milk spread across the first layer of brownies mixture. Then spread another layer of brownies on top. Then place the Oreo's into the brownie mixture and pour over the Biscoff spread. Finally top with the remaining third of brownies mixture.
Place the brownie in a preheat oven at 180°C for 35 minutes. Allow to cool fully before serving.