- Mix water, sugar, and yeast in a large bowl. Let it sit until frothy (about 5 minutes). 
- Add flour and salt, kneading into a smooth dough. 
- Cover the dough and let it rise for 30-45 minutes. Preheat oven to 425°F (220°C). Line a baking sheet with parchment paper. 
- Mix mozzarella, rosemary, and Parmesan for the filling. 
- Divide the dough into 8 portions, roll into ropes, flatten, and spoon filling into the center. 
- Fold the dough over the filling to seal, then shape into pretzels. 
- Dissolve baking soda in hot water. Dip each pretzel into the soda bath for 30 seconds and transfer to the baking sheet. 
- Top pretzels with Parmesan, salt, and rosemary. Bake for 15-20 minutes until golden brown. Cool briefly before serving.