In a medium non-aluminum saucepan over medium heat, warm the milk until small bubbles form along the edges, approximately 6 to 8 minutes, ensuring it does not boil. In a large mixing bowl, whisk the egg yolks with sugar, then incorporate cornstarch and salt until smooth. Gradually pour in half the hot milk, whisking continuously to temper the yolks, then add the remaining milk. Return the mixture to the saucepan and cook over medium heat, whisking constantly, until the cream thickens firmly, about 5 to 8 minutes. Stir in vanilla extract and transfer to a bowl, pressing plastic wrap directly onto the surface to prevent a skin from forming. Refrigerate for 2 to 3 hours.

Using a stand mixer with the paddle attachment or a handheld electric mixer, beat the softened butter and powdered sugar on medium-high until light and airy, about 3 minutes. Scrape down the bowl, then mix in the egg, followed by the vanilla extract and salt. Reduce the speed and add the flour and baking powder, blending just until a dough forms. Shape the dough into a disc, wrap it in plastic, and chill for at least 1 hour.

Preheat oven to 350°F (175°C). On a floured surface, roll the chilled dough to 1/8 to 1/4 inch thick. Carefully transfer it into a 9-inch tart pan with a removable bottom, pressing it into the sides and trimming the excess. Line the crust with parchment paper or foil, fill with pie weights or dried beans, and bake for 12 minutes. Remove the weights and lining, then bake an additional 10 to 15 minutes until golden and fully cooked. Allow to cool completely.

Spread the chilled pastry cream evenly in the cooled crust. Artfully arrange the fresh fruit over the cream. Lightly warm the apricot jam until fluid, and gently brush it over the fruit using a pastry brush to enhance sheen and preserve freshness.