Make the Pastry Cream: Heat the half-and-half, 6 tablespoons of the sugar, and the salt in a medium heavy-bottomed saucepan over medium heat until simmering, stirring occasionally to dissolve the sugar.
Meanwhile, whisk the egg yolks in a medium bowl until thoroughly combined. Whisk in the remaining 2 tablespoons sugar and whisk until the sugar has begun to dissolve and the mixture is creamy, about 15 seconds. Whisk in the cornstarch until combined and the mixture is pale yellow and thick, about 30 seconds.
When the half-and-half mixture reaches a full simmer, gradually whisk the simmering half-and-half into the yolk mixture to temper. Return the mixture to the saucepan, scraping the bowl with a rubber spatula; return to a simmer over medium heat, whisking constantly, until a few bubbles burst on the surface and the mixture is thickened and glossy, about 30 seconds. Off the heat, whisk in the butter and vanilla. Strain the pastry cream through a fine-mesh sieve set over a medium bowl. Press plastic wrap directly on the surface to prevent a skin from forming and refrigerate until cold and set, at least 3 hours or up to 2 days.
Make the Crust: Whisk together the yolk, cream and vanilla in a small bow; set aside. Place the flour, sugar and salt in a food processor and process briefly to combine. Scatter the butter pieces over the flour mixture; process to cut the butter until the mixture resembles coarse meal, about fifteen 1-second pulses. With the machine running, add the egg mixture and process until the dough just comes together, about 12 seconds. Turn the dough onto a sheet of plastic wrap and press into a 6-inch disk. Wrap in plastic and refrigerate at least 1 hour or up to 48 hours.
Remove the dough from the refrigerator (if refrigerated longer than 1 hour, let stand at room temperature until workable). Unwrap and roll out between 2 lightly floured large sheets of parchment paper or plastic wrap to a 13-inch round. Transfer the dough to a 9- to 9½-inch tart pan. Ease the dough into the pan corners and press the dough against the fluted sides of the pan. If some sections of the edge are too thin, reinforce them by folding the excess dough back on itself. Run the rolling pin over the top of the tart pan to remove the excess dough. Prick the bottom and sides of the dough all over with a fork. Set the dough-lined tart pan on a large plate and freeze for 30 minutes. (The dough-lined tart pan can be sealed in a gallon-size zipper-lock plastic bag and frozen up to 1 month.)
Preheat oven to 375 degrees F. Set the dough-lined tart pan on a baking sheet, press a square of foil into the frozen tart shell and over the edge, and fill with metal or ceramic pie weights. Bake for 30 minutes, rotating halfway through the baking time. Remove from the oven and carefully remove the foil and weights. Continue to bake until deep golden brown, 5 to 8 minutes longer. Set the baking sheet with the tart shell on a wire rack and cool to room temperature.
Assemble the Tart: Spread the cold pastry cream over the bottom of the tart shell, using an offset spatula or large spoon. Arrange the kiwi slices in an overlapping circle around the inside edge of the pastry. Arrange the raspberries in rings just inside the kiwi. Mound the blueberries in the center. (The tart can be refrigerated, uncovered, up to 30 minutes.) Remove the outer ring of the tart pan and place the tart onto a serving platter; serve.