Summer Blueberry Mascarpone Tart

Name: Summer Blueberry Mascarpone Tart
Ingredients: 1 1/4 cup all purpose flour; 1/4 rounded teaspoon salt; 1/2 cup ground walnuts; 1/2 cup plus 1 1/2 tablespoons unsalted butter, at room temperature; 1/4 cup sugar; 1/2 teaspoon vanilla extract; 12 ounce mascarpone; 2 tablespoons plus 1 teaspoon sugar; 4 cup fresh blueberries, rinsed & dried; 2 teaspoon cornstarch dissolved in two tablespoons warmish water; 2 tablespoon fresh lemon juice; 1/3 cup sugar; 2 tablespoon water; pinch of salt; zest from 1/2 a lemon (optional)