For the Tart Crust:

In the bowl of a stand mixer, combine the flour, powdered sugar, and salt. With the paddle attachment, stir the dry ingredients low to combine. Cut the butter into small chunks and add them to the flour mixture one at a time while the mixer is running on low. Continue to mix until it is all worked into the dry ingredients- it will look like slightly clumpy sand when it’s ready.

Grate the egg yolk with a microplaner or very small holed grater. Stir it into the butter and flour mixture. With the mixer still running, add the raw egg yolk, 2 tablespoons of cream, and vanilla extract. Stir until a dough is beginning to form. The dry ingredients should be completely absorbed, but you want to stop mixing while the dough is still in several smaller clumps and hasn’t come together into one large ball. If it’s too dry and isn’t forming a dough, drizzle in the third tablespoon of cream.

Place the dough on a sheet of plastic wrap and press it together into a ball, then flatten it into a disk about an inch thick. Wrap it tightly and refrigerate it for at least 2 hours or up to 3 days.

To bake the tart crust, preheat the oven to 375°.

Remove the dough from the refrigerator and roll it on a lightly floured surface into a round about 1/4″ thick. Carefully lift the dough into your tart pan and press it into edges and side. Allow any extra dough to hang over the sides, and either run your rolling pin over the edges to remove it or cut it off with a sharp knife. Refrigerate the tart crust for about 30 minutes.

Poke the crust 10-15 times with a fork, then line the crust with a sheet of parchment paper and fill it with baking weights, dry beans, sugar, or rice.

Bake the crust for 10 minutes, then remove it from the oven and lift the parchment paper with the weights from it. Return the crust to the oven and bake for another 5-8 minutes, or until the bottom crust is no longer shiny. The edges should be golden brown.

Remove it from the oven and cool completely before filling.

For the Blueberry Filling:

In a small pot, stir the blueberries, sugar, cornstarch and salt together. Heat it over medium low heat for 8-10 minutes. As the blueberries cook, they will burst and become juicy. The mixture will thicken as it cooks and is ready when the juices are no longer white or cloudy from the cornstarch.

Spread the blueberry filling over the bottom of the baked tart crust in an even layer. Put it in the refrigerator to cool.

For the Panna Cotta Layer:

Put the cold water in a small bowl. Sprinkle the powdered gelatin over it in an even layer and let it sit for 5-10 minutes, or until the gelatin has set and thickened.

In a medium pot, combine the whipping cream and sugar. Heat it over medium heat until it’s warm and steaming, but not boiling, and the sugar has dissolved.

Remove the cream from the heat and add the vanilla extract and vanilla bean paste. Whisk until it’s well combined, then stir in the set gelatin. Stir until it has dissolved.

Carefully spoon a thin layer of the panna cotta over the set blueberry layer, and allow it to set. Some of the blueberry layer may mix with it, but this thin layer will prevent the blueberries from mixing with the rest of the panna cotta and you’ll end up with a clean, white top.

Place the tart in the fridge for about 20 minutes, or until it’s set. Keep the rest of the panna cotta at room temperature, then pour it over the set tart. 

Carefully transfer the filled tart back to the refrigerator for at least 6 hours, or until the panna cotta is firm.

Serving and Storing the Blueberry Panna Cotta Tart

Once the panna cotta has set completely, you can cut and serve the tart. It’s optional, but decorating the top with sprigs of fresh mint and fresh blueberries is a lovely way to dress your tart up!

Serve the blueberry panna cotta tart cold. When cutting it, use a sharp, straight-edged knife to cut wedges. Wipe the knife down after each cut to keep the panna cotta white and clean.