Meanwhile, Heat oven to 350°F. In medium bowl, beat 3/4 cup mascarpone cheese, the sugar and 2 tablespoons lemon peel with electric mixer on low speed until blended. Add lemon juice, 2 tablespoons whipping cream and 1 teaspoon vanilla; beat until well blended. Add eggs and egg yolk, beating on low speed just until combined. Spread filling evenly in chilled crust. Place sheet of foil on rack below tart in case of spillover.