Heat your oven to 180ºC/160ºC fan and line two cupcake trays with cases
Beat the unsalted butter with the light brown sugar until light and fluffy
Combine the eggs, flour, cocoa powder with the butter/sugar mix and mix until well combined
If the mixture is too stiff you can add a little bit of milk at a time to get a smooth light consistency
Spoon the mixture into the cases evenly and bake in the oven for 15-20 minutes
Leave to cool fully on a wire rack
Buttercream Frosting
Beat the unsalted butter on its own with an electric whisk until smooth
Gradually add the icing sugar until all is combined and then add the vanilla extract and beat for another 3-4 minutes until smooth and fluffy
Add all of the marshmallow fluff that you can from the tub and beat the buttercream again for 3-4 minutes. If its too stiff or not combining very well then add the touch of milk!
Decoration
Transfer your marshmallow buttercream frosting to a large piping bag with your favourite piping tip (I use a 2D closed star piping tip!)
Pipe a swirl onto each of your cupcakes and top with a marshmallow. I then added some mini marshmallows to the surrounding buttercream.
ENJOY!
Notes
I like to mix my cupcake batter in two stages, creaming the butter and sugar together and then mixing everything else in at once, personally I find it works for me best but you can break it down more if you liked.
The original recipe is just for the cupcakes - they didn't have a marshmallow buttercream topping before the updated recipe!
Method: Beat the caster sugar with the unsalted butter until light and fluffy. Combine the eggs, cocoa, flour, 75g chocolate chips and 40g mini marshmallows until well combined. Divide the mixture between your cupcake cases evenly and sprinkle on the leftover chocolate chips and mini marshmallows. Bake in the oven for 15-20 minutes on 180ºC/160ºC fan and leave to cool fully.