Rose and Pistachio Cake

Preheat the oven to 180°C/Fan 160°C/Gas 4. Line the base of the cake tins with discs of baking parchment and butter the sides.

Cream the butter, sugar, rosewater and vanilla extract together in a bowl with an electric hand whisk or balloon whisk until light and fluffy. Gradually add the eggs, beating well between each addition. If it looks like the mixture is starting to curdle, add a couple of tablespoonfuls of the potato starch and beat again – it should come right.

Sift the potato starch, baking powder and ground almonds together over the mixture and fold in gently but thoroughly.

Scrape into the prepared tins and gently level the surface. Bake for 25–30 minutes until golden, springy to the touch and a skewer inserted into the centre comes out clean.

Leave in the tins for 10–15 minutes, then run a thin bladed knife around the inside of the tins. Turn out the cakes and place, right side up, on a wire rack. Leave to cool.

When the cakes are completely cold, whip the cream until thick, but not grainy. Put one of the cakes onto a plate and spread the cream almost to the edge. Place the other cake gently on top and twist it back and forth a little, just until the cream is peeking out between the layers.

 Pipe or spread the buttercream (recipe below) over the top of the cake, or top with more whipped cream. Sprinkle with chopped pistachios and scatter over a few fresh or crystallised rose petals if you have them.

Rose buttercream

This is not as sweet as a typical buttercream. Choose a delicious organic butter, as this is the major flavour. I generally use salted butter because I like the way it balances the sweetness; if you use unsalted, add a pinch of salt to bring out the butteriness. Take the butter out of the fridge about 20 minutes ahead to soften a little, but no longer than 30 minutes, or you will end up with icing that is too soft to use.

Put the icing sugar, butter and rosewater into a bowl and mash together with a wooden spoon until all the icing sugar is damp and the butter is broken down a bit. Swap to an electric hand whisk if you have one and beat until the mixture is starting to lighten.

Add the milk, 1 teaspoon at a time, beating well between each addition. You may not need all the milk, so check after 4 teaspoons to see if you like the texture.

Use a palette knife to spread the buttercream onto your cake(s), or pipe it on if you prefer. Buttercream made with dairy milk needs to be eaten within 48 hours; if using dairy-free milk, it keeps a little longer.

Cook's Tip: When adding the rosewater it's best to taste as you go – rosewater varies in strength and you may need less if you have a particularly strong one. If you're after a pink colour, add the merest drop of red food colouring – go for the palest sugar pink rather than candy floss.