Grease and line a 20cm (8inch) square cake tin.
Break up 100g (3 ½ oz) Dark Chocolate into pieces and place in a saucepan with the butter and sugar.
Heat very gently, stirring occasionally until melted.
Remove from the heat and cool for 10 minutes.
Whisk the eggs into the melted mixture to make a thick glossy batter.
Sift the flour on top and carefully mix all the ingredients together.
Pour into the prepared tin, smooth to the edges and chill in the fridge for 1 hour.
Meanwhile, preheat the oven to 180 ̊C (160 ̊C fan oven, 350 ̊F, gas 4).
To make the blondie layer, follow the same instructions for making the brownie batter as above, using 100g (3 ½ oz) White Chocolate -you will find that the melted mixture separates during melting, but once the eggs and flour are added,The mixture will blend together again.
Stir in the Caramel Flavour.
Carefully spread the White Chocolate batter over the brownie layer, trying not to press too heavily as you spread - there is no need to chill this layer.
The remaining 50g is to be used for the topping.
Bake for about 35 minutes until slightly risen, lightly golden and lightly crusty on top - the mixture should be slightly soft underneath. Leave to cool in the tin completely then remove from the tin, peel away the tin lining parchment and place the cake on a board.
For the topping, melt the remaining White Chocolate as above.
Put the popcorn in a bowl and squeeze in 50g (2oz) Dr. Oetker Salted Caramel Easy Fill Cake Centre and add the melted chocolate.
Mix well to make sure that all the popcorn is coated.
Squeeze the remaining Dr. Oetker Salted Caramel Easy Fill Cake Centre over the top of the cake and spread right to the edge.
Spoon over the caramel popcorn mix, and spread it out so that the whole top is thickly covered.
Pat it down a little using the back of a spoon.
Melt the remaining Dark Chocolate as above.
Using a teaspoon, drizzle the top all over with melted chocolate.
Leave in a cool place for a few minutes to set.
Using a large bladed knife, cut into 16 chunky pieces.
Your brownies are now ready to serve and enjoy!