Scallion Tartlets

Name: Scallion Tartlets
Ingredients: All-purpose flour, for work surface; 1 standard package (17.3 ounces) frozen puff pastry, thawed; 8 bunches scallions (2 1/4 pounds), trimmed and cut into matchsticks; 1 garlic clove, minced; 1 red Thai chile, ribs and seeds removed, minced; 1/2 cup walnuts (2 ounces), finely chopped; 1/2 cup Kalamata olives, pitted and coarsely chopped; 2 tablespoons extra-virgin olive oil; Coarse salt and freshly ground pepper; 1 large egg yolk; 1/2 cup freshly grated Parmesan cheese (2 ounces)