In a large mixing bowl, cream together 1 cup of cold unsalted butter and ½ cup of granulated sugar until light and fluffy, about 3-4 minutes. Add 1 large egg yolk and mix until combined. Gradually incorporate 2 cups of all-purpose flour and a pinch of salt, stirring until just combined. Shape the dough into a disc, wrap in plastic wrap, and refrigerate for at least 30 minutes.

Preheat your oven to 350°F (175°C). Lightly flour your work surface and roll out the chilled Pâte Sucrée into a ¼-inch thickness. Carefully transfer the rolled dough to a tart pan, pressing it into the bottom and sides. Prick the bottom with a fork to prevent bubbling, then bake for 20-25 minutes until the crust is golden brown. Remove from the oven and let it cool completely.

In a saucepan over medium heat, combine 2 cups of whole milk and the seeds from 2 vanilla beans, stirring gently until warm, but not boiling. In a separate bowl, whisk together ½ cup of granulated sugar, 3 large eggs, and ¼ cup of cornstarch until smooth. Slowly pour the warm milk into the egg mixture while whisking continuously, then return the mixture to the saucepan.

Cook the combined mixture over low heat, stirring constantly, for about 5-7 minutes until it thickens and bubbles gently. Once thickened, remove it from the heat and stir in 4 tablespoons of unsalted butter until fully melted and incorporated. Pour the pastry cream into a bowl and cover with plastic wrap, pressing it directly onto the surface to prevent a skin from forming. Let it cool completely.

Once the vanilla bean pastry cream has cooled, carefully remove the cling wrap and fill the cooled tart crust with the creamy mixture. Spread it evenly to create a smooth top, then refrigerate the tart for at least 2 hours to allow the flavors to meld and the cream to set properly.

Just before serving your Decadent Tart with Silky Vanilla Bean Pastry Cream, decorate the top with fresh berries and toasted almond slivers for a lovely presentation. Finish with a light dusting of powdered sugar for added sweetness and elegance. Slice and serve chilled.