In a medium bowl, combine the flour, cornstarch, salt and butter. Using two forks or a pastry cutter, cut the butter into the flour until the butter resembles oat flakes or tiny peas. Add the egg and use a fork to combine the flour mixture with the egg. Dump the mixture out onto a floured surface. Work the dough until it starts to hold together. The dough is a little tougher than your average when working with it; don't be alarmed. If you're making individual tarts, roll the dough out, place the individual tart pans on the dough and cut a circle 1-1/2 to 2 inches larger than your pan, rework leftover dough as necessary to form more tarts. If you're using a 9-inch tart pan, roll the dough out into a 12-inch circle. Place the dough at the base of the pan, work out any air bubbles, crimp edges. Refrigerate the tart-shell(s) for 10 minutes while you prepare the tart filling.
FOR THE TART FILLING:
Place a rack in the center of the oven and preheat the oven to 400° F.
In a medium bowl, combined the egg, heavy cream, milk, 4 tablespoons of Parmesan cheese, red pepper flakes, garlic powder, basil, salt and pepper and whisk until combined. Fold in the goat cheese. Divide filling into tartshell(s). Top with the remaining 2 tablespoons of Parmesan cheese. Place the tart pan(s) on a baking tray and bake for 24 to 27 minutes for individual tarts and 30 to 35 minutes for large tart. For a darker crust, bake an additional 1 to 2 minutes. Let cool 10 to 15 minutes before serving.
4 ounces of Cheddar or mozzarella cheese can be used in place of the goat cheese.