Heat panini press to medium-high heat; spray with cooking spray (or you can use a grill pan).
Spread mustard on 4 slices of bread; top with one slice of cheese.
Drizzle honey on remaining undressed slices of bread; top with one slice of cheese, two pieces of prosciutto and six baby spinach leaves. Top with the remaining cheese topped slice of bread.
Cook on panini press for three to five minutes or until golden brown. Cut each sandwich in half to serve.
Keywords American, Back to School, Blends, Entertaining, Fall, Nut Free, Pork, Sandwiches/Wraps, Soy Free, Spring, Summer, Winter