Pistachio Whoopie Pies

I’ve made whoopie pies twice before, the first time was an undisputed success (carrot cake whoopie pies went down a treat at my 19th birthday party) and the second was an absolute disaster (chocolate and peanut butter – didn’t rise, dry and hard as rocks). I almost owed it to myself to try again and this time decided to go with pistachio. I’m a big fan of pistachio - particularly in macaroons - and was keen to attempt to give this all-American pie an elegant twist. It has to be said: these had to be the best whoopie pies I’ve ever made. They rose well, were light and fluffy, and the pistachio was a welcome addition.

These would be an inventive alternative to the traditional cupcakes or fairy cakes at a birthday party – they still have the consistency of a cake but are unusual, can be made with all kinds of flavours and are a lot more original addition to a party menu! I’m thinking of making them a little smaller and using the pistachio flavour next summer for my 21st: hopefully they’ll fit with whatever I plan to do…

The recipe comes from The Hummingbird Bakery’s Cake Days, and you can find it below. For me, pistachio is almost a spring-appropriate flavour (but work well in the summer too!) – these whoopie pies would be delicious eaten outside on a crisp sunny day with a glass of wine, so I suggest you make them fast before we lose what little summer we’ve had to the depths of a cold, rainy and traditional British autumn!

Ingredients:
For the sponge:
1 large egg
150g caster sugar
125g plain yoghurt
25ml whole milk
2 tsp vanilla essence
75g unsalted butter, melted
275g plain flour
¼ tsp baking powder
¾ tsp bicarbonate of soda
60g-80g (depending on how nutty you want the whoopie pies) ground pistachios (if you can’t find ready-ground pistachios in a shop – I couldn’t – then just buy pistachio kernels and whizz them up in a food processor with a blade attachment or a spice grinder)

For the filling:
170g unsalted butter, softened
280g icing sugar
A tub (around 220g) of vanilla marshmallow fluff

Method:

Using a hand-held electric mixer, whisk the egg and sugar until pale and fluffy. Pour the yogurt and milk into a jug, add the vanilla essence and stir together, then tip the mixture into the creamed egg and sugar and mix until evenly incorporated. Add the melted butter and mix.

Sift together the flour, baking powder and bicarbonate of soda, and then add to the mixture in 2 batches, mixing thoroughly after each addition. Stir in the ground pistachios by hand, making sure they are evenly mixed into the batter. Then place the mixture in the fridge to cool and set for 20-30 minutes.

Preheat the oven to 170 degrees Celsius (325 degrees Fahrenheit), Gas Mark 3, and line several baking trays with baking parchment. The whoopie pies need to be approximately 5cm in diameter and all roughly the same size. Because you’ll be sticking them together, it’s really important to make sure they’re an even shape: every time I’ve made them before I’ve assumed they’re the same size before they went in the oven only to have them all come out completely different, making it a nightmare to pair them up! To combat this potential disaster area, I drew round a 5cm diameter egg cup as a template on the parchment. Point to mention, ideally, there needs to be a 2-3cm gap between each circle to allow for spreading during baking.

Once the batter has cooled, spoon the mixture on to the circles on the trays.

Place them in the oven and bake for 10-13 minutes or until the sponges are lightly golden on top and bounce back when gently pressed. Allow them to cool slightly and then transfer to a wire rack.

While they are cooling, make the filling. Using a hand-held electric mixer slowly mix together the butter and icing sugar until fully blended. Mix in the marshmallow fluff, then increase the speed and beat until light and fluffy. Place the frosting in the fridge for about 30 minutes to firm up slightly.

Once the sponges have cooled completely, match up evenly sized pairs. They should all technically be the same, but it’s worth making trying out all different combinations for a more uniform appearance overall. Spread the flat side of one of the sponges with about 1 tablespoon of filling, adding a little more if needed. Sandwich the other half of the corresponding pair on top, with the flat side facing down, and then repeat with the remaining sponges and filling.

This recipe makes around 10 pies, but it can be more or less depending on how big you make them. I only used about 60g of pistachios but they could have done with more: if you’re going to give them a go then I’d suggest using closer to 75/80g – just add as much as you feel is necessary. Also, I had a bowl of the filling left over (Hummingbird recipes always overestimate how much frosting you need) which I used for more whoopie pies, whose recipe will follow soon. Try these out: this is a classy variation of a whoopie pie that will NOT disappoint!