1. Stir together the mayonnaise and pesto and let sit covered at room temperature for about 20 minutes so the flavors can blend.

2. Preheat a panini press to medium heat. Cut each square of focaccia bread in half and spread each side with a generous tablespoon of pesto mayonnaise. Layer in order: 1 slice of cheese, 2 ounces of turkey, 1 ounce of prosciutto, 1/2 cup of arugula, and the second slice of cheese.

3. Close the paninis and cook in the press until the cheese is fully melted and the bread has those telltale grill marks. Slice in half along the diagonal and serve immediately.