Jersey Black Butter and Walnut Tart

**Prepare the Pastry:** In a large bowl, rub the cold Jersey butter into the plain flour and icing sugar until the mixture resembles breadcrumbs. Alternatively, pulse in a food processor.

Add the mashed Jersey Royal potato and egg yolk, then gradually add the cold water, mixing until the dough just comes together. Be careful not to overmix.

Flatten the dough into a disc, wrap in cling film, and chill in the refrigerator for at least 30 minutes.

**Preheat and Roll:** Preheat oven to 180°C (160°C fan/Gas Mark 4). On a lightly floured surface, roll out the pastry to a 3mm thickness.

**Line the Tin:** Carefully lift the pastry and line the 9-inch tart tin, gently pressing it into the corners. Trim any excess pastry and prick the base with a fork.

**Blind Bake:** Line the pastry case with baking parchment and fill with baking beans or rice. Bake for 15 minutes, then remove the parchment and beans, and bake for a further 5-10 minutes until the pastry is pale golden.

**Prepare the Filling:** While the pastry is baking, gently warm the Jersey Black Butter in a saucepan over low heat until it is smooth and slightly loosened. Be careful not to boil it.

Toast the chopped walnuts lightly in a dry pan until fragrant. This will enhance their flavour and texture.

**Assemble and Bake:** Spread the warmed Jersey Black Butter evenly over the base of the partially baked pastry case.

Sprinkle the toasted walnuts evenly over the Black Butter filling.

Brush the pastry edge with the beaten egg.

Bake in the preheated oven for 20-25 minutes, or until the filling is set and the pastry is golden brown.

**Cool and Serve:** Let the tart cool in the tin for at least 15 minutes before carefully removing it. Serve warm or at room temperature, with a dollop of Jersey cream or ice cream if desired.