In a large mixing bowl, combine warm water, yeast, and sugar. Let it sit until the mixture is frothy, about 5-10 minutes.
Add half of the flour and salt to the yeast mixture and stir until combined. Gradually add the remaining flour until a soft dough forms.
Turn the dough onto a floured surface and knead until smooth and elastic, about 10 minutes.
Place the dough in a greased bowl, cover with a cloth, and let it rise in a warm place until doubled in size, about 1 to 1 1/2 hours.
Preheat the oven to 350°F.
Roll out the dough on a floured surface into a rectangle. Spread softened butter over the dough, then sprinkle minced garlic, chopped parsley, and shredded mozzarella evenly on top.
Cut the dough into squares and stack them into a greased 9x5-inch loaf pan. Let it rise again until puffy, about 30 minutes.
Bake in the preheated oven for 30 minutes, or until the top is golden brown.
Let the bread cool for 10 minutes before pulling apart to serve.