Spread 1 side of 6 bread slices with blue cheese. Layer with turkey, cranberry sauce, pancetta, and arugula. Spread 1 side of remaining 6 bread slices with mustard, and place, mustard sides down, on arugula.
Note: We tested with Saga Classic Soft-Ripened Blue-Veined Cheese.
Bacon-Horseradish-Turkey Sandwiches: Substitute 6 split croissants for bread, 6 Havarti cheese slices for blue cheese, 6 cooked bacon slices for pancetta, and peach preserves for cranberry sauce. Stir 1 Tbsp. refrigerated horseradish into peach preserves. Proceed as directed.