In a large mixing bowl, combine 2 cups of warm water and the 4 teaspoons of instant yeast. Let it sit for about 5 minutes until it becomes frothy.
In a separate bowl, whisk together 9 cups of all-purpose flour, 1 cup of sugar, and 1 tablespoon of Kosher salt.
Once the yeast is activated, add the dry ingredients to the yeast mixture gradually. Mix with a wooden spoon or dough scraper until a shaggy dough forms.
Add the 3 tablespoons of cubed unsalted butter to the dough. Continue mixing until the butter is incorporated.
Turn the dough out onto a lightly floured surface. Knead for about 10 minutes until the dough is smooth and elastic.
Place the dough in a greased bowl, cover it with a clean kitchen towel, and let it rise in a warm place for about 1 to 1.5 hours, or until it has doubled in size.
After the first rise, punch down the dough to release air bubbles. Divide the dough into 2 equal portions and shape each into a loaf.
Cover the loaves with the kitchen towel again and let them rise for an additional 30-45 minutes until they have risen above the edges of the pans.
While the dough is rising, preheat your oven to 350°F (175°C).
Once the dough has risen, brush the tops with the melted unsalted butter. Place the pans in the preheated oven and bake for 25-30 minutes.
Remove the loaves from the oven and let them cool in the pans for about 10 minutes. Then transfer to a wire rack to cool completely.
