Lightly dust work surface with flour. Use a rolling pin to roll the dough out to a 10 x 13-inch rectangle, with the long side facing you.
Brush the melted butter all over the dough. Sprinkle ½ cup of the Parmesan cheese over the butter. Add a layer of the pepperoni, overlapping each slice slightly, leaving a 1-inch border along the edges of the dough. Then add a layer of the salami over the pepperoni, also slightly overlapping. Top with sliced prosciutto and then cheese.
Use your hands to start rolling the dough inwards, lengthwise. Continue rolling until the other side of the dough is reached. Carefully pinch the edges to form a seal. Also, use your hands to fold in and seal both ends of the stromboli.
Transfer to a baking sheet, seam side down. Cut three diagonal slits in the top of the stromboli. Brush the egg wash all over the tops and sides and then sprinkle 1 tbsp of Parmesan cheese and the dried oregano over the top. Place in the preheated oven and bake for 30 minutes, or until golden on top.
Remove from the oven and let rest for 5 to 10 minutes. Use a serrated knife to cut the stromboli into 1-inch slices. Place on serving platter and serve with warmed marinara sauce.
We love the combination of pepperoni, salami, prosciutto, and whole milk mozzarella. Other common stromboli filling ingredients include deli ham and shredded provolone cheese. We think homemade pizza dough makes a big difference in the final dish, but often you can find excellent pizza dough available for purchase from your local pizza place or Italian eatery. The stromboli is best when served warm, but it's also delicious at room temperature.Homemade marinara is the perfect dipping sauce for this stromboli.