I had never ventured into whoopie pie territory before, obviously! Unfortunately, they spread too far and flattened out quite a bit, but they tasted great! If I make them again, I’ll make smaller ones and stiffen the batter a bit more.

But the filling! The filling! OMG! Awesome!

Makes 9 large whoopie pies

Cake

350g (2 4/5 cups) all-purpose (plain) flour
2 tsp baking powder
1/2 tsp salt
115g (1 stick, 1/2 cup) butter, room temperature
300g (1 1/2 cups, packed) muscovado (dark brown) sugar
1 tsp vanilla extract or paste
2 medium eggs
160 ml (2/3 cup) whole cream

Whisk together flour, baking powder and salt in a bowl. Set aside.

Using a stand mixer fitted with a whisk attachment, or a hand-held electric mixer, beat butter and muscovado sugar on medium-high speed until combined. Add vanilla, then beat in the eggs well, one at a time.

Using a paddle attachment or spatula, mix in the flour in 3 batches, alternating with the cream in 2 batches, until just combined.

Line 2 baking sheets with parchment paper. Scoop 18 mounds of batter onto the baking sheets, about 5cm (2″) apart (about 2 tbsp batter per cake). Gently form into rounds with damp fingers and smooth the tops. Refrigerate until firm, at least 30 minutes.

Preheat oven to 200°C (400°F). Bake the cakes one sheet at a time in centre of oven until they spring back when gently pressed, about 15 minutes. Cool 5 minutes on sheets, then remove from parchment to a rack to cool completely.

Dulce de leche buttercream

160g (1/2 cup) dulce de leche
60 ml (4 tbsp) heavy cream
16g (2 tbsp) all-purpose (plain) flour
115g (1 stick, 1/2 cup) unsalted butter, room temperature
100g (1/2 cup) granulated (white) sugar
pinch salt

In a medium, heavy-bottomed saucepan, whisk the dulce de leche and cream together and heat gently until combined. Add the flour and whisk to combine, then, whisking constantly over medium heat, cook until the mixture comes to a simmer and thickens, about 8 minutes. Transfer mixture to a clean bowl and set aside to cool to room temperature.

Using a stand mixer fitted with a whisk attachment, or a hand-held electric mixer, beat the butter and sugar until pale and fluffy. Add salt and mix in.

With the mixer on medium speed, add the cooled dulce de leche mixture one tablespoon at a time until fully incorporated and you have a light and fluffy frosting.

Pipe or spoon the filling onto half the cakes and top with the remaining halves.