In a large mixing bowl, combine all-purpose flour, powdered sugar, and salt. Add the cold, cubed unsalted butter and cut it into the dry ingredients until the mixture resembles coarse crumbs. Next, mix in the egg yolk and cold water gradually until the dough holds together. Shape the dough into a disk, wrap it in plastic wrap, and chill in the refrigerator for 30 minutes.

Preheat your oven to 350°F (175°C) while the dough chills. On a lightly floured surface, roll out the chilled dough to about 1/8 inch thick. Use a round cookie cutter to cut circles of dough, ensuring they fit into your mini tart pans. Gently press each circle into the pans, ensuring an even layer at the bottom and sides. Place them in the refrigerator while you prepare the filling.

Remove the tart shells from the fridge and use a fork to prick the bottom of each one to prevent bubbling. Line them with parchment paper and fill with pie weights or dried beans. Bake in the preheated oven for 10 to 12 minutes, or until the edges turn golden brown. Carefully remove the parchment and weights, then let the crusts cool completely before adding the custard filling.

In a small saucepan over medium heat, gently warm the heavy cream and whole milk until steam rises, but do not boil. Remove from heat and add dried culinary lavender to infuse for about 10 minutes. After steeping, strain the mixture through a fine mesh sieve to remove the lavender buds, ensuring a smooth custard base for your Mini Salted Honey Lavender Pies.

In a mixing bowl, whisk together honey, granulated sugar, large eggs, vanilla extract, and fine sea salt until well combined. Gradually add the strained lavender-infused milk and cream, whisking continuously until the mixture is smooth. Pour this luscious custard into the cooled tart shells, filling them about three-quarters full, to allow for slight expansion while baking.

Carefully place the filled tart shells in the oven and bake at 350°F (175°C) for 15 to 18 minutes. The custard should be set around the edges but still slightly jiggly in the center when done. This soft texture ensures delicious creaminess in your Mini Salted Honey Lavender Pies. Once baked, remove them from the oven and allow to cool completely on a wire rack.

Once the pies have cooled, dust them lightly with powdered sugar for a touch of sweetness and elegance. Finish with a sprinkle of flaky sea salt to enhance the flavors beautifully. For an extra flourish, add fresh lavender sprigs as a garnish. Your Mini Salted Honey Lavender Pies are now ready to be enjoyed at your spring gathering or whenever you crave a taste of floral bliss!