Blackberry crumble cake with pistachio custard

Ingredients

For the cake

• 230g/8oz unsalted butter, plus extra for greasing
• 20ml/¾fl oz neutral oil (such as vegetable or sunflower)
• 220g/7¾oz golden caster sugar
• 4 free-range eggs
• pinch sea salt
• 1 tsp vanilla bean paste
• 200g/7oz self-raising flour
• ½ tsp baking powder
• 30g/1oz ground almonds
• 300g/10½oz blackberries, chopped
• 30g/1oz pistachios, chopped
• 30g/1oz plain flour
• 40g/1½oz demerara sugar
• 20ml/¾fl oz double cream

For the custard

• 250ml/9fl oz full-fat milk
• 250ml/9fl oz double cream
• 1 tsp vanilla bean paste
• pinch sea salt
• 100g/3½oz caster sugar
• 5 free-range egg yolks
• 20g/¾oz pistachio paste

Method for Blackberry crumble cake

1. To make the cake, preheat the oven to 180C/160C Fan/Gas 4. Grease a 24x24cm/9.5×9.5in square tin with butter and line with baking paper.

2. Put the butter, oil and golden caster sugar in a stand mixer or in a bowl. Cream together using the paddle attachment or a hand-held electric whisk until pale and fluffy. Beat in the eggs one at a time, followed by the salt and vanilla. Fold in the flour, baking powder and almonds. Pour the cake mixture into the tin and top with the chopped fruit.

3. Mix together the pistachios, flour and demerara sugar in a bowl. Use your fingertips to breadcrumb the cream in to create little clusters of crumble – do not over-mix. Scatter all over the cake and fruit. Bake for about 45 minutes–1 hour, until a skewer inserted comes out clean. Leave the cake to cool before removing from the tin.

4. To make the pistachio custard, stir together the milk, cream, vanilla, salt and half of the caster sugar in a saucepan and place over a medium heat.

5. Meanwhile, in a separate heatproof bowl, whisk the egg yolks, pistachio paste and remaining sugar to combine. When the milk is steaming hot and just about to come to the boil, slowly and carefully pour two-thirds of the milk mixture over the yolks mixture. Whisk vigorously as you pour until the mixture is smooth and combined.

6. Pour the yolk mixture back into the pan with the remaining milk, reduce to a low heat and whisk well to incorporate. Stir with a spatula constantly until it coats the back of a spoon. Remove from the heat and serve with slices of the cake. This cake will keep in the fridge in an airtight container for three days.

Blackberry crumble cake with pistachio custard