For the gluten-free sponge cakes
To prepare the gluten-free sponge cakes start heating the oven to 180°C (160° fan).
Grease 12 mini sandwich tins.
Beat the butter and sugar in a mixing bowl until light and fluffy.
Add the eggs, one at a time, beating well to combine. Add the flour and salt and mix well.
Spoon into the tins and bake for about 15 minutes until golden and springy to the touch.
Cool in the tins for 5 minutes, then place on a wire rack to cool completely.
For the gluten-free sponge cakes filling
Beat the butter and vanilla until creamy.
Sift in the icing sugar and beat until thick and smooth.
Split the cakes in half and spread half the cakes with a thin layer of jam.
Spoon the buttercream into a piping bag and pipe on top of the jam.
Place the gluten-free sponge cake tops and sift icing sugar over the top.