1 tablespoon unsalted butter
1/2 yellow onion, diced
1 tablespoon flour
3/4 cup low-sodium chicken broth
1 10-ounce box frozen peas and carrots
1 3- to 4-pound store-bought rotisserie chicken, meat shredded
kosher salt and black pepper
2 refrigerated 9-inch piecrusts (from a 15-ounce package, such as Pillsbury)
Heat oven to 400° F. Melt the butter in a saucepan over medium heat. Add the onion and cook for 3 minutes.
Add the flour and cook, stirring constantly, for 1 minute.
Slowly stir in the broth. Cook until thickened, about 3 minutes. Add the peas and carrots, chicken, and ¼ teaspoon each salt and pepper. Remove from heat.
Cut each piecrust in half. Spoon the chicken mixture over one side of each half-circle, leaving a ½-inch border. Using your fingers, wet the border with water. Fold the crust over the chicken. Press to seal. Make three 1-inch slits in the top of each.
Transfer the empanadas to a baking sheet. Bake until golden, 15 to 18 minutes.