Preheat your oven to 375°F first.
Line your baking sheet with parchment paper.
Let the pizza dough rest at room temperature.
This makes rolling easier and prevents tearing.
Flour your work surface lightly.
Roll dough into a large rectangle.
Aim for about 12x15 inches.
Make it roughly ¼ inch thick.
Even thickness helps it cook uniformly.
Spread Dijon mustard over the dough.
Leave a 1-inch border around edges.
Layer the chicken evenly across the surface.
Add chopped ham on top of chicken.
Sprinkle both cheeses over everything.
Season with garlic powder, salt, and pepper.
Starting from the long side, roll tightly.
Pinch the seam closed very well.
Tuck the ends underneath the roll.
This prevents filling from leaking out.
Place seam-side down on baking sheet.
Mix melted butter with beaten egg.
Brush this mixture over the entire stromboli.
Make 3-4 diagonal slashes on top.
This lets steam escape while baking.
Bake for 25-30 minutes until golden brown.
The internal temperature should reach 165°F.
Let it cool for 5 minutes.
This helps cheese set slightly.
Slice into thick pieces with sharp knife.
Serve warm and enjoy immediately!