In a medium saucepan, combine 2 cups of whole milk, 1 cup of heavy cream, and half of the sugar. Heat until simmering. Whisk remaining sugar, cornstarch, and egg yolks in a bowl. Temper the egg mixture with warm milk; return to saucepan and cook, stirring constantly, for 5 minutes until thickened. Stir in butter, vanilla, and cognac. Chill for at least 2 hours.

In a food processor, combine 1 1/2 cups of flour, 1/2 cup of confectioners' sugar, and a pinch of salt. Cut in 1/2 cup of cold unsalted butter until resembling coarse crumbs. Mix in 1 tablespoon of heavy cream, 1 egg, and 1 teaspoon of vanilla extract; shape into a disk and refrigerate for 1 hour.

Preheat oven to 400°F (204°C). Roll out the chilled dough to fit a tart pan. Place dough in the pan, pressing into edges; trim excess. Line crust with parchment paper, fill with pie weights, and bake for 10 minutes. Remove weights, lower temperature to 350°F (177°C), and bake for an additional 5-6 minutes until golden brown. Cool completely.

Spread chilled pastry cream over the cooled tart shell. Arrange fresh seasonal fruit artfully on the creamy filling. Heat apricot preserves until melted; brush over the fruit.

Remove tart from pan and slice into wedges for serving. Enjoy immediately.