2. Combine butter and mustard. Spread butter mixture on one side of each slice of bread. Top 4 slices evenly with pancetta, Italian sausage, onion mixture and cheese. Cover with second slice of bread.
3. Grill sandwiches in heated panini press 3 to 4 minutes or until bread is golden and cheese is melted. Cut in half and serve.
Nutritional information per serving: Calories 1219; Total Fat 66g; Saturated Fat 27g;