In a large mixing bowl, combine 1 ½ cups of warm water, 1 packet of instant yeast, and 1 tablespoon of sugar. Let sit for approximately 5 minutes until frothy.

In another bowl, whisk together 4 cups of all-purpose flour and 1 ½ teaspoons of salt. Gradually pour the yeast mixture into the flour, mixing until a soft dough forms, then knead until smooth and elastic, about 5 minutes with a mixer or 8 minutes by hand.

Fold in 1 tablespoon of chopped rosemary and ½ cup of grated Parmesan cheese.

Shape the dough into a ball and place it in a greased bowl, turning to coat. Cover and let it rise in a warm place until doubled in size, about 1 hour.

Preheat your oven to 425°F (220°C). Punch down the dough gently, divide into 8 pieces, flatten each piece, and place a cube of mozzarella in the center. Fold the dough over, pinch to seal, and shape into a pretzel.

In a large pot, bring 4 cups of water to a boil and stir in ¼ cup of baking soda. Boil each pretzel for 30 seconds, then drain and transfer to a parchment-lined baking sheet.

Brush with melted butter and sprinkle with sea salt. Bake for 12-15 minutes until golden brown.