Pour 1 and 1/3 cups (320ml) of warm water (100–110°F) into the bowl of a stand mixer. Add 2 and 1/4 teaspoons (7g) of yeast and 1 tablespoon (13g) of sugar. Whisk briefly, then cover the bowl and let it sit undisturbed for 5 minutes until slightly foamy.
Add 2 tablespoons (30ml) olive oil, 1 teaspoon salt, and 3 and 1/2 cups (450g) flour to the yeast mixture. Mix on low speed for 2 minutes until a rough dough forms.
Switch to the dough hook and knead on medium speed for a full 5 minutes, or turn the dough out onto a lightly floured surface and knead by hand for 5 minutes. If the dough is sticky, add flour just 1 teaspoon at a time. The finished dough should feel soft and just slightly tacky — poke it and it should slowly spring back.
Lightly oil a large bowl, place the dough inside, and turn it to coat all sides. Cover with plastic wrap or a kitchen towel and let it rise at room temperature for 60 to 90 minutes, or until the dough has doubled in size.
Preheat your oven to 400°F (204°C). Line two large baking sheets with parchment paper. Punch the risen dough down firmly to release the air, then cut it into two equal portions. Set one aside or freeze it for another time.
On a lightly floured surface, roll each dough portion into a roughly 10×16-inch rectangle using a lightly floured rolling pin. If the dough keeps pulling back, cover it and let it rest 10 minutes, then try again.
Stir 2 minced garlic cloves into 3 tablespoons (43g) melted butter. Brush this garlic butter across the full surface of each dough rectangle, then scatter 2 teaspoons of chopped parsley on top. Layer on your sliced meats and cheese, keeping a 1-inch border along the bottom and sides and a 3-inch border along the top. Use about 1/2 pound of meat and 1/2 pound of cheese per stromboli.
Brush all exposed dough edges (including the top 3-inch border) with egg wash made from 1 beaten egg and 1 tablespoon water. Starting from the bottom, slowly roll the dough into a tight 16-inch log, tucking in both ends as you go. Keep the roll firm and even.
Transfer each stromboli seam-side down onto a prepared baking sheet. Pinch the ends closed. Brush the entire outside with egg wash, sprinkle on any optional toppings (flaky salt, Parmesan, herbs), and use a sharp knife to cut 3 to 4 slits across the top of each to allow steam to escape.
Bake at 400°F (204°C) for about 25 minutes until the crust is deep golden brown and an instant-read thermometer inserted into the center reads at least 200°F (93°C). If baking both at once, rotate the pans halfway through and add 2 to 3 extra minutes if needed. Allow the strombolis to cool on the pan for 5 full minutes before slicing and serving. Serve warm with marinara sauce on the side.