Step 1: Make the Dough (if not using store-bought)

1. Activate the Yeast: In a small bowl, combine the warm water, sugar, and yeast. Stir gently and let it sit for about 5 minutes until it becomes foamy. This means the yeast is activated and ready to use.

2. Mix the Dough Ingredients: In a large mixing bowl, combine the flour and salt. Make a well in the center, then add the foamy yeast mixture and olive oil. Stir until the dough begins to come together.
3. Knead the Dough: Transfer the dough to a floured surface and knead for about 8-10 minutes until it becomes smooth and elastic. If you’re using a stand mixer, knead with the dough hook on medium speed for 5-6 minutes. The dough should be slightly tacky but not sticky; add a little more flour if needed.
4. First Rise: Place the dough in a lightly oiled bowl, cover with a clean kitchen towel or plastic wrap, and let it rise in a warm, draft-free area for about 1 hour, or until it has doubled in size.

Step 2: Prepare the Filling

1. Slice the Pepperoni: If your pepperoni slices are large, cut them in half or quarters so they fit neatly into the rolls. Set aside.
2. Grate the Cheese: Use freshly shredded mozzarella if possible for the best melt and texture.

Step 3: Roll Out and Fill the Dough

1. Preheat the Oven: Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
2. Divide the Dough: Punch down the risen dough to release any air bubbles. Transfer it to a floured surface and roll it into a rough rectangle, about 12×14 inches in size. Cut the dough into 12 even squares (about 3×3 inches each).
3. Add the Filling: Place a small handful of shredded mozzarella and a few slices of pepperoni in the center of each dough square.
4. Shape the Rolls: Fold the corners of each square over the filling, pinching the edges together to seal. Roll the dough in your hands to form a smooth ball, ensuring the seam is on the bottom to prevent the filling from leaking out.

Step 4: Second Rise and Prepare the Topping

1. Second Rise: Place each filled dough ball, seam-side down, on the prepared baking sheet, spacing them a couple of inches apart. Cover lightly with a kitchen towel and let them rest for 10-15 minutes while you prepare the garlic butter.
2. Make the Garlic Butter: In a small bowl, combine the melted butter, minced garlic, and chopped parsley. Brush each roll with the garlic butter mixture, saving a little for after baking. Optionally, sprinkle a small amount of grated Parmesan on each roll for extra flavor.

Step 5: Bake the Pepperoni Rolls

1. Bake: Bake the rolls in the preheated oven for 15-18 minutes, or until they’re golden brown and the cheese is melted inside. Rotate the pan halfway through baking for even browning.
2. Brush with Remaining Garlic Butter: As soon as the rolls come out of the oven, brush them with any remaining garlic butter for an extra layer of flavor.
3. Cool Slightly: Allow the rolls to cool on the baking sheet for a few minutes before serving. The cheese inside will be hot, so cooling slightly makes them easier to eat.