1 1/2 cups all-purpose flour
1/2 teaspoon salt, plus 1/2 teaspoon
3 tablespoons butter, cut into small pieces
1 1/2 tablespoons lemon juice
1/2 cup mascarpone cheese
3 tablespoons ice water
2 ounces diced pancetta
1 teaspoon chopped fresh thyme (or rosemary, oregano, parsley, or a combination)
1 1/2 to 2 cups leftover side dish vegetables (like sauteed mushrooms and shallots)
1/2 cup grated cheese (try a combo of smoked mozzarella and fontina)
1/4 teaspoon freshly ground black pepper
2 tablespoons freshly grated Parmesan
1 large egg, lightly beaten