Preheat oven to 180ºC / 160ºC Fan/ Gas 4/ 350ºF
Line a square 20cm baking tin with baking parchment
In a small suacepan set over a medium heat cook the raspberries and 2 tablespoons of caster sugar for a few minutes until all the sugar has dissolved and the raspberries have broken down slightly. Set aside for later.
In a saucepan set over a low heat melt together the chocolate and butter. Set aside to cool.
In a large mixing bowl add the eggs, caster sugar and brown sugar. Mix until light and frothy.
Stir the vegetable oil in to the melted chocolate.
Pour the melted chocolate into the large mixing bowl. Using a metal spoon, stir the ingredients together in large looping movements until the mixture is dark and combined.
Add the flour, salt and cocoa powder to the mixing bowl and fold together very gently until you can no longer see white streaks of flour.
Tip the brownie mixture into the prepared tin and smooth it with a spatula.
Randomly add spoonfuls of Marshmallow Fluff on top of the brownie mixture then use a chopstick (or similar) and swirl the Marshmallow Fluff into the brownie mixture.
Poke pieces of Wagon Wheels into the brownie mixture.
Dot spoonfuls of raspberries over the top of the brownie mixture. Use the back of a spoon to push the raspberries into the brownie.
Bake in the centre of a preheated oven for 25 minutes.
Leave the Wagon Wheel Brownies to cool completely in the pan before turning out and cutting into 15 slices.