Turkey and Cheese Roll Up

Name: Turkey-and-Cheese Roll-Up
Ingredients: 1 cup (2 sticks) unsalted butter, divided; 1 large onion, finely chopped, optional; 3/4 cup raw rice; 1 1/2 cups chicken broth; Pepper, to taste; 1/4 cup minced fresh parsley, optional; 10 sheets filo dough (read the box carefully for defrosting instructions); 4 ounces smoked turkey, cut into fine strips; 4 ounces Swiss cheese, grated (about 1 cup); 4 ounces cheddar, grated (about 1 cup)