A tender, buttery pâte sucrée crust cradles a light, vanilla-flecked mascarpone cream, finished with a glossy crown of vibrant fresh fruit for an elegant yet effortless dessert.
Lightly grease a 9-inch tart pan with a removable base with nonstick spray.
Make the crust: In a food processor, pulse together flour, confectioners’ sugar, and salt to combine.
Add the room-temperature butter 1 tablespoon at a time, pulsing a few times after each addition.
Add the cold egg and pulse only until the dough comes together in a soft clump.
Transfer dough to a lightly floured surface, press into a 1-inch-thick disc.
Press dough evenly into the prepared tart pan and up the sides. Use the bottom of a measuring cup to press edges firmly. Trim or flatten the rim; patch thin spots with scraps.
Dock the bottom all over with a fork. Cover and freeze for at least 30 minutes (or up to 1 day).
Preheat oven to 350°F (177°C). Place the tart pan on a baking sheet and bake for 25 minutes or until the crust appears set. Cool completely on a rack.
Make the cream filling: Using a mixer with a whisk attachment, whip the heavy cream, 6 Tbsp (45g) confectioners’ sugar, lemon zest, vanilla extract, and vanilla bean seeds to stiff peaks, about 3–4 minutes.
In a small bowl, gently mix the mascarpone with the remaining confectioners’ sugar just until smooth (do not overmix).
Fold the whipped cream into the mascarpone mixture until combined and smooth.
Spread the vanilla mascarpone cream evenly into the cooled crust.
Arrange assorted fresh sliced fruit decoratively on top.
In a small bowl, whisk the preserves with water to thin, then brush the glaze over the fruit for a glossy finish.
Slice and serve. Refrigerate leftovers.