In a medium saucepan, heat 1 cup of whole milk, 1 cup of heavy cream, and ½ cup of sugar over medium heat until simmering. In a bowl, whisk together ⅓ cup of cornstarch and 4 egg yolks until creamy. Gradually temper the egg mixture with warm milk, then return to the saucepan. Cook over medium heat, whisking constantly until thickened, 5-7 minutes. Remove from heat, stir in 2 tbsp of butter and 1 tsp of vanilla extract. Cool before chilling in the refrigerator for at least 2 hours.

In a mixing bowl, whisk together ¾ cup of heavy cream, 1 egg, and 1 tsp of vanilla extract. In another bowl, combine 1 ½ cups of all-purpose flour, ¼ cup of confectioners' sugar, and a pinch of salt. Cut in ½ cup of cold unsalted butter until resembling coarse crumbs. Pour heavy cream mixture into flour mixture, stirring until a dough forms. Chill in plastic wrap for 1 hour.

Preheat oven to 400°F (204°C). Roll out chilled dough to ¼ inch thick and fit into a 9-inch tart pan. Prick the bottom with a fork, chill for 15 minutes. Line with parchment paper, fill with weights, bake for 10 minutes. Lower oven to 350°F (177°C), remove weights and parchment, prick again, bake for 5-6 minutes until golden. Cool completely.

Spread chilled pastry cream evenly inside cooled crust with a spatula. Arrange seasonal fruits on top of custard. If desired, warm ¼ cup of apricot preserves and brush over fruit.

Carefully remove the tart from the pan and slice into wedges. Serve chilled, pairing with whipped cream or vanilla ice cream.