Step 1

Grease and line the base and sides of two 20cm round cake pans with baking paper. Preheat oven to 180°C. Melt the butter in a saucepan over low heat.

Step 2

Add oil, then remove from heat and set aside to cool. Whiz pistachios in a food processor until very finely ground. Place in a bowl and sift in all the dry ingredients. Make a well in the centre. Add butter mixture, yoghurt, eggs and vanilla, and whisk to make a loose batter.

Step 3

Divide batter between pans, then bake for 25 minutes or until golden and a skewer inserted into the centre comes out clean. Cool in the pans for 10 minutes, then turn out onto a wire rack to cool slightly.

Step 4

Meanwhile, whisk the lemon curd and mascarpone in a bowl until thick. Chill until needed. Combine the lemon juice and 25g icing sugar in a pan over low heat, stirring, until mixture is clear. Set aside to cool.

Step 5

While cakes are still warm, pierce all over with a skewer, then slowly drizzle 1 tbs lemon syrup over each cake. Set cakes aside to cool completely.

Step 6

When cakes are cool, slice each cake in half horizontally so there are four cake layers. Place one cake layer on a plate and spread with one-third lemon curd mixture. Repeat layering two more times, finishing with a final layer of cake.

Step 7

Combine remaining icing sugar and lemon syrup to make a thick icing, adding a little water to loosen if necessary. Stir in lemon zest, then drizzle the icing over the cake, letting it drip down the sides. Scatter the chopped pistachios over the cake to serve.