In a mixing bowl, combine 220 g of plain flour, 40 g of powdered icing sugar, ¼ teaspoon of fine salt, and 6 g of ground Earl Grey tea leaves. Rub in 110 g of unsalted butter until the mixture resembles coarse crumbs. Add 1 lightly beaten egg and 15-30 ml of ice-cold water, mixing until the dough forms. Wrap it in cling film and chill for about 1 hour until firm.

Once chilled, roll out the dough on a lightly floured surface to fit a 23 cm (9-inch) tart tin, ensuring it's about 3 mm thick. Gently press the dough into the tin, trim the edges, and refrigerate it overnight to allow it to rest and prevent shrinking during baking.

Preheat your oven to 180°C (350°F). Dock the pastry base with a fork, line it with parchment paper, and fill with baking weights or dried beans. Bake for 15 minutes until lightly golden, then remove the weights and parchment. Brush the base with an egg wash (1 egg + 1 tbsp milk) and bake for an additional 10 minutes until golden and fully set.

In a saucepan, heat 480 ml of double cream over medium heat until it starts steaming, but do not let it boil. Add 2 Earl Grey tea bags and steep for 20 minutes, allowing the cream to absorb the tea's aromatic flavors. After steeping, remove the tea bags and set the cream aside to cool slightly.

In a large mixing bowl, whisk together 6 large egg yolks and 70 g of caster sugar until the mixture turns a pale yellow color. Gradually pour in the warm cream while whisking continuously to temper the egg yolks. Once combined, strain the mixture through a fine sieve into a jug to ensure a silky custard.

Pour the custard filling into the prepared tart shell, smoothing it out gently. Bake in the preheated oven at 150°C (300°F) for 40 minutes, until the custard is set around the edges but still slightly wobbly in the center. Allow the tart to cool at room temperature for a while before refrigerating.

After chilling the tart in the fridge for 2-4 hours, remove it. Sprinkle 40-60 g of caster sugar evenly over the surface of the cooled custard. Using a kitchen blow torch, carefully caramelize the sugar until it bubbles and turns a deep golden color.