Butter an 11-inch fluted tart pan with a removable bottom with 2 teaspoons of butter and set aside.

Make the pastry by combining the flour, salt, lemon zest, and confectioners' sugar in a mixing bowl. Add the butter and, using a pastry cutter, 2 knives, or your hands, work in butter until mixture resembles coarse crumbs. Combine the egg and orange liqueur in a small bowl and add to the flour mixture. Using a fork, stir until the mixture just comes together. Turn dough out onto a lightly floured surface and knead just until a dough is formed. Shape into a flattened disk, wrap in plastic, and transfer the dough to the freezer for 15 minutes.

Place the dough on a floured surface and roll into a 13-inch round. Transfer dough to the prepared tart pan and ease dough into the edges and up the sides of the pan. Trim excess dough. Transfer to the refrigerator for 30 minutes.

Preheat the oven to 375 degrees F.

Remove the tart shell from the refrigerator and prick it all over with the tines of a fork. Line the pastry with aluminum foil or parchment paper and fill with pie weights or dried beans. Bake the crust until the edges just begin to turn golden, about 15 minutes. Remove from the oven and remove the pie weights and aluminum foil and bake for an additional 10 minutes, or until the crust is light golden brown. Remove from the oven and set aside on a wire rack to cool.

Make the filling by combining the blood orange juice, orange zest, brown sugar, and mascarpone in a mixing bowl; whisk until smooth. Add the eggs and egg yolks, 1 at a time, beating after each addition. Add the liqueur and stir until smooth. Pour the filling into the cooled tart shell. Bake until the filling is lightly browned in spots and the crust is golden, about 25 minutes. Let cool completely. Dust with confectioners' sugar and serve.