In a large bowl, combine the plain flour, chilled unsalted butter, and flaky sea salt until the mixture resembles fine breadcrumbs.

Gradually add cold water, mixing until the dough just comes together. Shape it into a disc, wrap in cling film, and chill in the refrigerator for at least 30 minutes.

Preheat your oven to 200°C (400°F). Toss the peeled and sliced pumpkin with olive oil and roast for 20-25 minutes.

Wilt the spinach in a skillet over medium heat for about 3-4 minutes, then drain well.

In a mixing bowl, whisk together the eggs, egg yolk, double cream, Parmesan, nutmeg, and black pepper.

Roll out the pastry dough and line the tart tins, then chill for 15 minutes.

Blind bake the pastry shells for 15 minutes, then remove the weights and bake for another 5 minutes.

Assemble the tarts by layering the wilted spinach, roasted pumpkin, and crumbled Gorgonzola, then pour the custard mixture over it.

Bake in the oven for 25-30 minutes, then let cool for 10 minutes before serving.