Chocolate Chip Whoopie Pies

Great for birthday party's !

ingredients

fore the sponge

1 large egg
150g of caster sugar
125g plain yogurt
25ml of milk
1/4tsp of vanilla essence
75g of unsalted butter
melted
275g of plain flour
3/4 tsp of bicarbonate of soda
1/4 tsp baking powder 
150g dark chocolate chips
minimum 70 per cent coca solid

for the filling

170g  unsalted butter  softened
2 tbsp cocoa powder
280 icing sugar
220g vanilla
marshmallow fluff

1. Using a hand held electric whisk or a freestanding electric mixer with the paddle attachment , whisk the egg and the sugar until pale and fluffy .
2. Pour the yogurt , milk and vanilla essence into a jug . Mix together by speed until combined . Pour in the melted butter and mix again .
3. Sift together the flour, bicarbonate of soda  and the baking powder then add these dry ingredients to the batter in two stages , mixing thoroughly to ensure everything is well combined. Stir in the chocolate chips in by hand , then place the finished batter in the fridge to allow to cool and set for 15 minutes.
4. In the meantime preheat the oven to 170 c 325F gas mark 3,and line two baking trays with baking parchment.
5. Spoon the batter on to the trays making 16 to 20 mounds , each  3-5 cm .Bake in the oven for 10 min or until a light golden colour on top and the sponges bounce back when gently pressed .Allow to cool completely on a wire rack before you add filling.
6. While the sponges are cooking , and using the electric whisk or freestanding mixer with the paddle attachment  , mix together the butter, marshmallow fluff and continue to beat , on a high speed . chill in the fridge 30 minutes to firm up.
7. To assemble the whoopie pies , take on sponge and spread about 2 tablespoons  of the filling on the flat side and then sandwich with another sponge , with the flat side facing down .Continue doing this until all the sponge and frosting has been used.