In a medium bowl, whisk together the egg yolk, cream, and vanilla until smooth. In a food processor, pulse together the all-purpose flour, confectioners' sugar, and kosher salt. Add the chilled unsalted butter and blend until the mixture resembles coarse crumbs. Slowly incorporate the egg mixture until a dough forms. Wrap in plastic wrap and chill for 1 hour to ensure it firms up.

Preheat your oven to 350°F (175°C). On a lightly floured surface, roll the chilled dough into an 11-inch circle, aiming for an even thickness. Fit the dough into a 9-inch tart pan, pressing gently into the corners and trimming any excess edges. Prick the bottom with a fork to prevent bubbling, then pre-bake for 10-12 minutes until the crust is golden and fragrant. Let it cool completely before filling.

In a medium saucepan over medium heat, whisk together the eggs, lemon juice, lemon zest, honey, and a pinch of salt. Cook the mixture, stirring constantly, until it thickens and reaches 165°F (74°C), about 8-10 minutes. Once thickened, strain the lemon curd through a fine-mesh sieve into a bowl to remove any clumps. Stir in the chilled butter and cream until smooth, then pour the curd into the cooled tart crust.

In a blender or food processor, puree the blueberries until smooth. Strain the puree through a fine mesh to eliminate skins and seeds, collecting the liquid in a saucepan. Stir in honey and cornstarch, then bring to a simmer over medium heat. Cook while stirring for about 3-5 minutes until thickened and glossy. Carefully pour the warm blueberry mixture over the lemon curd layer, ensuring an even distribution.

Refrigerate the tart for at least 2 hours, allowing the layers to set properly. Once chilled, slice the tart into wedges and serve as a refreshing dessert.