Step 1: Prepare the Tart Crust - Combine the all-purpose flour, kosher salt, and powdered sugar in a food processor. Add the cold, cut pieces of unsalted butter and pulse until the mixture resembles coarse crumbs.
Step 2: Form the Dough - Add the vanilla extract to the crumb mixture and pulse again until the dough begins to come together. It should be slightly crumbly but hold its shape when pressed.
Step 3: Chill the Dough - Turn the dough onto a lightly floured surface and shape it into a disk. Wrap it in plastic wrap and refrigerate for at least 30 minutes.
Step 4: Preheat the Oven - Preheat your oven to 350°F (175°C).
Step 5: Roll Out the Dough - Roll out the dough on a floured surface to about 1/8 inch thick. Cut out circles that fit your tart pan or muffin tin.
Step 6: Bake the Tart Shells - Press the dough circles into the tart pan or muffin tin. Prick the bottoms with a fork and bake for 12-15 minutes or until golden brown.
Step 7: Make the Cream Filling - In a mixing bowl, combine the heavy whipping cream, mascarpone cheese, softened cream cheese, and powdered sugar. Whisk until smooth and creamy.
Step 8: Assemble the Tarts - Fill each shell with a generous spoonful of the cream filling and smooth it out.
Step 9: Top with Fresh Fruit - Arrange your choice of fresh fruits on top of the cream filling.
Step 10: Chill and Serve - Place the assembled tarts in the refrigerator for at least 30 minutes before serving.
