- Preheat the Oven:** 
- - Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper or lightly grease it. 
- **Prepare the Dough:** 
- - On a lightly floured surface, roll out the pizza dough into a large rectangle, approximately 12x14 inches. 
- **Assemble the Stromboli:** 
- - In a small bowl, mix together the Dijon mustard and mayonnaise (if using). Spread this mixture evenly over the dough, leaving about 1 inch of space around the edges. 
- - Layer the Swiss cheese slices down the center of the dough, followed by the deli ham slices. 
- - Evenly distribute the cooked chicken breast over the ham. 
- - Carefully fold the sides of the dough over the filling, then roll the dough tightly from one long edge to the other, creating a log shape. Pinch the seams and ends to seal the Stromboli. 
- **Add Toppings:** 
- - Place the Stromboli seam-side down on the prepared baking sheet. 
- - Brush the top of the Stromboli with melted butter, then sprinkle it with garlic powder, dried parsley, and grated Parmesan cheese. 
- **Bake the Stromboli:** 
- - Bake the Stromboli in the preheated oven for 25-30 minutes, or until the crust is golden brown and crispy. 
- - Remove the Stromboli from the oven and let it rest for about 5 minutes before slicing. 
- **Serve:** 
- - Slice the Chicken Cordon Bleu Stromboli into pieces and serve warm. Pair it with a simple green salad or a dipping sauce like honey mustard or marinara.