In a large mixing bowl, combine warm water, sugar, and yeast. Let it sit for 5 minutes until it becomes frothy.

Add flour and salt to the yeast mixture, kneading until a smooth and elastic dough forms. Cover the bowl with a clean cloth and let the dough rest for 30-45 minutes, allowing it to double in size.

In a small bowl, combine mozzarella cubes, chopped rosemary, and grated Parmesan cheese to make the filling.

Preheat the oven to 425°F (220°C) and line a baking sheet with parchment paper.

Divide the risen dough into 8 equal portions. Roll each portion into a long rope. Flatten each rope slightly and spoon the mozzarella and rosemary filling onto the center. Fold the dough over the filling and seal the edges, forming a pretzel shape.

In a large saucepan or kettle, bring 4 cups of water to near boiling. Remove from heat and add baking soda, stirring until dissolved.

Carefully lower each pretzel into the baking soda bath for 30 seconds, then transfer them to the lined baking sheet.

Sprinkle grated Parmesan cheese generously over each pretzel and garnish with a few fresh rosemary leaves.

Bake the pretzels in the preheated oven for 15-20 minutes, or until they turn golden brown and the cheese crust becomes crispy.

Allow the pretzels to cool slightly before serving.