Preparation

• To make the crust, preheat oven to 350 degrees. In a bowl, stir together the flour, sugar, and kosher salt. Pour in the olive oil and use a fork to mix the dough together. (No need to chill the dough).
• Place the crust dough into the tart pan and use your fingers to press the dough to fit the pan, coming all the way up the sides of the pan. Bake for 22-25 minutes, or until the dough is baked and light golden brown in color. Set aside to cool.
• For the filling, cream together the mascarpone, powdered sugar, vanilla, and zest of one lemon. Spread evenly in the cooled tart crust. Place in refrigerator to chill.
• For the topping, bring the blueberries, water, and sugar to a low boil in a saucepan over medium heat. Reduce heat and simmer for 2-3 minutes, until the blueberries have popped. In a small bowl, whisk together the cornstarch and juice of one lemon. Pour the cornstarch mixture into the saucepan and stir for another minute. Let the blueberry sauce cool completely.
• Once the blueberry sauce topping has cooled completely, spoon the mixture over top of the chilled tart; fill just until the top is covered. Any leftover topping can be served on the side.