In a small bowl, combine warm water (about 105–115°F / 40–46°C), sugar, and active dry yeast. Stir gently and let sit 5–10 minutes until foamy. If it doesn't foam, the yeast may be inactive — start again with fresh yeast.

Mix dough

In a large bowl, whisk together the flour and salt. Make a well in the center and pour in the foamy yeast mixture and 2 tablespoons olive oil. Stir with a wooden spoon or dough scraper until a shaggy dough forms.

Knead dough

Turn the dough out onto a lightly floured surface and knead for 6–8 minutes until smooth and elastic. Alternatively, knead in a stand mixer with a dough hook on medium speed for 5–6 minutes.

First rise

Lightly oil a clean bowl with 1 teaspoon of olive oil, place the dough ball inside, turn once to coat, cover with plastic wrap or a damp towel, and let rise in a warm draft-free spot until doubled in size, about 60–75 minutes.

Filling / Assembly

Prepare filling ingredients

While the dough is rising, shred the mozzarella, grate the parmesan, measure out pizza sauce, pepperoni, and dried seasonings so everything is ready.

Shape dough

After the dough has doubled, gently deflate it and turn it out onto a lightly floured surface. Roll or press the dough into a rectangle about 12 x 8 inches (roughly 1/2-inch thick).

Spread sauce and add fillings

Spread the 1 cup of pizza sauce evenly over the dough, leaving a 1/2-inch border on one long edge. Sprinkle about 1 1/2 cups of shredded mozzarella evenly over the sauce, then arrange pepperoni slices on top. Reserve about 1/2 cup mozzarella and the grated parmesan for topping.

Roll or fold

Starting from the long side opposite the border, tightly roll the dough into a log, sealing the edge with the bare border. Pinch or crimp the seam to seal. Optionally, tuck the ends under to seal loaf ends. You can also fold the rectangle into a pocket style (enclose fillings and pinch seams) if preferred.

Second rise in pan

Place the seam-side down loaf into a greased 9 x 5-inch loaf pan or onto a parchment-lined baking sheet seam-side down for a freeform loaf. Cover loosely with plastic wrap or a towel and let rise until puffy, about 30–40 minutes (it will not double again but should be noticeably puffed).

Finish / Bake

Preheat oven

Preheat the oven to 375°F (190°C) while the shaped loaf is finishing its rise.

Egg wash and topping

Whisk the egg with 1 teaspoon water to make an egg wash. Brush the top of the loaf lightly with egg wash. Brush a little olive oil over the loaf as well for a glossy crust. Sprinkle the reserved 1/2 cup mozzarella, grated parmesan, dried oregano, and red pepper flakes evenly over the top.

Bake

Bake in the preheated oven for 25–30 minutes if in a loaf pan (or 20–25 minutes on a baking sheet) until the crust is golden brown and the internal temperature reaches about 200°F (93°C). If the top browns too quickly, tent loosely with foil for the last 5–10 minutes.

Cool and slice

Remove from the oven and let the loaf rest in the pan for 10 minutes, then transfer to a wire rack to cool slightly (another 10–15 minutes) before slicing. Letting it rest prevents the cheese and sauce from running out when sliced.

Serve

Slice into 1-inch thick slices and serve warm. Optionally serve with extra warmed pizza sauce for dipping.