In a large mixing bowl, beat together unsalted butter and granulated sugar until creamy and fluffy, about 3 minutes. Gradually add all-purpose flour and one egg, mixing until a soft dough forms. Shape the dough into a disc, wrap in plastic wrap, and refrigerate for 30 minutes until firm.

Preheat your oven to 350°F (175°C). Roll out the chilled dough to a ¼-inch thickness. Transfer it to a tart pan and press it into the edges, trimming any excess. Prick the bottom with a fork and bake for 20 minutes or until golden brown. Allow the crust to cool completely on a wire rack.

In a saucepan over medium heat, combine whole milk and the seeds scraped from vanilla beans, heating until just below boiling. In a separate bowl, whisk together egg yolks and sugar until pale. Gradually whisk in the warm milk mixture, then return it to the saucepan. Cook on low heat, constantly whisking, until the mixture thickens, about 5–7 minutes.

Once the pastry cream has thickened, remove it from the heat and transfer it to a bowl. Cover the surface with plastic wrap pressed directly onto the cream to prevent a skin from forming. Allow the pastry cream to cool at room temperature for 15 minutes before refrigerating for at least 2 hours, until fully chilled and set.

Once the crust has cooled and the pastry cream is chilled, remove the cream from the refrigerator. Gently spoon the silky vanilla bean pastry cream into the cooled tart crust, spreading it evenly. Smooth the top with a spatula for an elegant finish.

Top the tart with fresh berries for a pop of color and flavor. Lightly dust with powdered sugar and sprinkle toasted almond slivers for a delightful crunch. Optionally, add mint leaves on top before serving.