. Make the Tart Shells:

• Preheat the oven to 350°F (175°C). Grease and flour tart pans or a muffin tin (if using).
• In a food processor, pulse together the flour, powdered sugar, and cold cubed butter until the mixture resembles coarse crumbs.
• Add the egg yolk and pulse again until the dough starts to come together. Add ice water 1 tablespoon at a time, pulsing until the dough forms a ball.
• Turn the dough out onto a floured surface and knead it briefly to bring it together. Wrap the dough in plastic wrap and refrigerate for at least 30 minutes.
• Roll out the dough to about 1/8-inch thickness and carefully press it into the tart pans. Trim any excess dough. Prick the bottoms with a fork to prevent air bubbles.
• Line the tart shells with parchment paper and fill with pie weights or dried beans. Bake in the preheated oven for 12-15 minutes, or until the edges are golden brown. Remove the parchment paper and weights, then bake for an additional 5 minutes.
• Let the tart shells cool completely.

2. Prepare the Earl Grey Panna Cotta Filling:

• In a small saucepan, heat the heavy cream, milk, and sugar over medium heat until it just begins to simmer.
• Add the Earl Grey tea bags (or loose leaf tea in a tea infuser) to the saucepan. Let it steep for 5-7 minutes, then remove the tea bags or tea infuser.
• In a small bowl, sprinkle the gelatin over the cold water and let it sit for 5 minutes to bloom.
• Once the cream mixture is infused with the tea, remove it from the heat and stir in the bloomed gelatin until dissolved.
• Add the vanilla extract and stir to combine. Let the mixture cool slightly.

3. Assemble the Tarts:

• Pour the Earl Grey panna cotta mixture into the cooled tart shells, dividing it evenly among the tarts.
• Refrigerate the tarts for at least 4 hours, or overnight, until the panna cotta filling is fully set.

4. Garnish and Serve:

• Once the panna cotta has set, garnish the tarts with fresh berries, candied citrus peel, or mint leaves as desired.
• Serve chilled and enjoy the creamy, aromatic delight of these Earl Grey panna cotta tarts.