.chicken a la king recipe

4 tablespoons butter - 1/4 cup all-purpose flour - 2 cups chicken broth - 1 cup heavy cream (or whole milk) - 1/2 teaspoon salt - 1/4 teaspoon black pepper - 1/4 teaspoon paprika - 2 cups cooked chicken, diced or shredded - 1 cup mushrooms, sliced - 1/2 cup frozen peas, thawed - 1/2 cup diced pimientos (optional) - 1/4 cup dry sherry (optional) - 4 puff pastry shells or 4 slices of toast