Prepare the dough: In a large bowl, combine the warm water, sugar, and active dry yeast. Stir and let it sit for 5-10 minutes, or until the yeast is foamy.

Make the dough: Add the flour and salt to the yeast mixture. Mix together to form a dough. Knead the dough on a lightly floured surface for about 5-7 minutes, or until smooth and elastic.

Let the dough rise: Place the dough in a lightly oiled bowl, cover with a damp cloth, and let it rise for about 45 minutes, or until it doubles in size.

Prepare the mozzarella filling: While the dough is rising, mix the mozzarella cubes, chopped rosemary, and grated Parmesan cheese in a small bowl. Set aside.

Shape the pretzels: Preheat your oven to 450°F (232°C). Punch down the dough after it has risen. Divide the dough into 8 equal pieces. Roll each piece into a long rope (about 12 inches long). Press the center of each rope to create a space for the filling. Place a spoonful of the mozzarella mixture in the center and fold the dough over to seal the cheese inside, pinching the ends to make sure it’s tightly closed.

Boil the pretzels: In a large pot, bring 4 cups of water to a boil. Add the baking soda to the boiling water. Carefully lower each stuffed pretzel into the water for about 30 seconds, then remove using a slotted spoon and place it on a baking sheet lined with parchment paper.

Bake the pretzels: Bake the pretzels in the preheated oven for 18-20 minutes, or until golden brown and crispy.

Finish the pretzels: After baking, remove the pretzels from the oven. Immediately sprinkle with grated Parmesan cheese and garnish with fresh rosemary leaves.

Serve: Serve the mozzarella-stuffed soft pretzels warm, with extra cheese or marinara sauce for dipping if desired.