First, make the lemon and passionfruit drizzle. Halve the passionfruit and sieve the pulp into a small bowl, reserving the seeds. Stir 2 tbsp of the Lemon Curd into the juice and set aside. Stir the remaining Lemon Curd into the ground almonds and set aside. Wash about 2 tsp of the passionfruit seeds and leave to dry.
Heat the oven to 180C, 160 fan, gas mark 4. Grease and flour a 1 litre bundt mould, a 900g loaf tine or a 20cm, deep, round cake tin.
Beat the butter and caster sugar together until light and fluffy then add the eggs one at a time with a tablespoon of the flour. Beat well until smooth.
Beat in the sour cream and lemon zest. Finally fold in the remaining flour and baking powder.
Spoon half the cake mixture into the prepared mould or tin then dot the Lemon Curd and almond mixture evenly over the top. Finish with the remaining cake mixture.
Bake for 45 mins then cover the top loosely with foil and continue to bake for a further 30-40mins or until a skewer inserted into the middle comes out clean.
Leave the cake to cool for 10mins then turn out onto a wire rack placed over a plate. Make fine holes in the sponge using a cocktail stick and spoon the lemon and passionfruit drizzle over the cake whilst warm. Leave to cool.
Sprinkle with passionfruit seeds, pistachio nuts and dust lightly with icing sugar to serve.
If using a bundt mould such as ours, it's best to lightly grease it and dust with flour until completely coated. Turn upside down and tap the mould to remove any excess flour.
If you want to use another tin, it should be a 1 litre capacity one.