To prepare the pastry, start by combining plain flour, fine sea salt, icing sugar, and cold butter in a food processor. Pulse the ingredients until they resemble fine breadcrumbs. In a separate small bowl, mix 3 tablespoons of cold water with 2 egg yolks. Add this mixture to the food processor and pulse until everything is well combined. Transfer the dough to a bowl, shape it into a ball, cover, and refrigerate for 30 minutes.
To prepare the compote, start by placing the blackberries (keep 8 aside) and 130g of caster sugar in a pan. Cook them over low heat for 5 minutes until they break down. Then, increase the heat and simmer for an additional 10 minutes until the mixture becomes syrupy.
Craft a paste by combining cornflour with a spoonful of syrup in a cup, then gently stir it into the compote. Allow it to cool before incorporating amaretto, lemon zest, and juice.
Start by rolling out the pastry on a lightly floured surface to form a 25cm circle, roughly the thickness of a £1 coin. Gently line a 20cm fluted tart tin with the pastry, allowing an overhang, and then place it in the freezer for 20 minutes. Meanwhile, preheat your oven to 200°C/180°C fan/gas 6.
Begin by lining the pastry with baking paper and filling it with baking beans (or dried rice). Bake for 15 minutes, then remove the paper and beans. Continue baking for an additional 7 minutes. Finally, trim any excess using a serrated knife.
To prepare the frangipane, begin by whisking together the softened butter and the remaining 150g of sugar until well combined. Next, incorporate the sea salt, orange zest, ground almonds, almond extract, 3 beaten eggs, and self-raising flour into the mixture. Continue to beat for an additional minute for a perfectly blended result.
Spread compote over the pastry (reserve 4 tbsp for serving), add frangipane, top with reserved blackberries, flaked almonds, and bake for 45 mins or until golden (cover with foil after 30 mins if browning too fast). Cool in the tin, dust with icing sugar, and serve with clotted cream or crème fraîche, extra blackberries, and a drizzle of reserved compote.