Whisk together 1 egg yolk, 1 tablespoon cream, and ½ teaspoon vanilla in a bowl.
Process 1 ¼ cups flour, ⅓ cup confectioners' sugar, and ¼ teaspoon salt in a food processor until combined, about 5 seconds.
Add 8 tablespoons chilled butter to the mixture and pulse until it resembles coarse cornmeal, about 15 pulses.
With the processor running, add the egg yolk mixture and process until the dough just comes together, about 12 seconds.
Form dough into a 6-inch disk, wrap in plastic wrap, and refrigerate for 1 hour or up to 4 days.
Let the dough sit at room temperature for about 10 minutes before rolling.
Roll the dough into an 11-inch circle on a lightly floured surface.
Loosely roll dough around the rolling pin and transfer to a 9-inch tart pan with removable bottom.
Press the dough gently into the corners and sides of the pan.
Trim excess dough by running a rolling pin over the top of the pan.
Wrap the dough-lined pan loosely in plastic, freeze for 30 minutes until firm.
Adjust the oven rack to the middle and preheat to 375ºF.
Place the chilled dough on a baking sheet, cover edges with aluminum foil, and fill with pie weights.
Bake for 30 minutes, rotating halfway through, until the crust is golden and set.
Remove the foil and weights and allow the crust to cool completely.
Preheat the oven to 350ºF.
Whisk 7 tablespoons lemon juice, ¼ cup lemon zest, 1 egg, 5 yolks, ⅓ cup honey, and a pinch of salt in a saucepan until smooth.
Cook over medium-low heat, stirring constantly with a rubber spatula until the mixture thickens and reaches 165ºF, about 5 minutes.
Off the heat, whisk in 4 tablespoons chilled butter until melted.
Strain the curd through a fine-mesh strainer and stir in 2 tablespoons cream.
Pour the warm lemon curd into the cooled tart crust.
Bake for 10-12 minutes until the curd is opaque and jiggles slightly when shaken.
Cool the tart on a wire rack for about 10 minutes.
Process 2 cups blueberries in a food processor until smooth, about 2 minutes.
Strain the purée through a fine-mesh strainer into a saucepan, pressing to extract the juice.
Whisk in ¼ cup honey and a pinch of salt.
Combine 2 tablespoons cornstarch with 2 tablespoons water in a small bowl, then whisk into the blueberry mixture.
Simmer over medium-low heat for 4 minutes, stirring constantly, until the mixture thickens and reaches 170ºF.
Off the heat, whisk in 1 tablespoon reserved lemon juice.
Pour the blueberry mixture evenly over the lemon curd.
Refrigerate for 2 hours until the blueberry layer is set and shiny.
Remove the outer ring of the tart pan, then slide a metal spatula between the tart and the pan bottom.
Carefully transfer the tart to a serving platter.