Ingreadient

• butter, for the pan
• flour, for the pan
• 1 9-inch unroll-and-bake refrigerated pie crust
• 1 large egg white, lightly beaten
• 2 teaspoons vegetable oil
• 3 ounces pancetta, cut into 1/4-inch pieces
• 5 large eggs, at room temperature
• 1/2 cup (4 ounces) mascarpone cheese, at room temperature
• 2 cups (8 ounces) shredded gruyere cheese
• 3 scallions, white and pale green parts, thinly sliced
• 1/2 teaspoon kosher salt
• 1/2 teaspoon freshly ground black pepper