Place the flour, butter and sugar in the bowl of a food processor and process in short bursts until the mixture resembles fine breadcrumbs.

While the food processor is running, add the egg yolks and vanilla. Process until the dough just comes together and forms a ball around the blade.

Remove dough and turn out onto a piece of plastic wrap and form a ball. Flatten into a disc, wrap tightly in the plastic wrap and refrigerate for 1 hour.

Preheat oven to 350 degrees and spray a tart pan with non-stick spray. Remove the pastry dough from the refrigerator and roll it out about 1/8 inch thick. (It may be easiest to roll the dough out between 2 sheets of parchment paper.) Line the prepared tart pan with the pastry. Carefully lift and place the dough into the corners. (Do not stretch the dough.) Trim the edges and prick the bottom of the dough with a fork. Return the dough to the refrigerator for at least 30 minutes.

After the dough has chilled, cut a piece of parchment paper the appropriate size to line the bottom and sides of the dough. Place the parchment over the dough and fill the inside with pie weights. (If you don’t have pie weights, just use uncooked rice or beans.)

Bake the crust for 10 minutes before removing the pie weights and parchment paper. Return the crust to the oven and bake for an additional 10 minutes or until golden brown on the edges and pale in the center. Remove from the oven and set aside to cool completely.

While the crust is cooling, make the mascarpone filling by placing the mascarpone, lemon zest, powdered sugar, vanilla and salt into a medium-sized mixing bowl. Beat well with a whisk or wooden spoon until completely combined. Cover with plastic wrap and refrigerate until the crust is completely cool.

Spread the filling evenly in the bottom of the cooled tart shell and top with the fresh blueberries. Dust with a little bit of powdered sugar and fresh lemon zest before serving. Enjoy!