In a large mixing bowl, combine 1 cup warm water and 1 teaspoon granulated sugar. Sprinkle the 1 teaspoon active dry yeast over the top and let it sit for about 5-10 minutes, or until it becomes frothy.
Once the yeast is frothy, add 2 tablespoons olive or canola oil, 2 cups of all-purpose flour (reserve 1/2 cup for later), and 2 teaspoons salt to the bowl. Mix until a rough dough forms.
Transfer the dough to a floured surface and knead it gently for about 5 minutes, adding the reserved flour as necessary until the dough is smooth and elastic.
Shape the dough into a ball and place it back in the mixing bowl. Cover it with a kitchen towel and let it rise in a warm area for about 20 minutes.
While the dough is rising, preheat your skillet over medium heat. Once hot, add 3 tablespoons melted butter and swirl it around to coat the bottom and sides.
After the dough has risen, punch it down and transfer it to the skillet. Press and stretch the dough to fit the shape of the skillet, creating dimples with your fingers.
Sprinkle 1 tablespoon grated Parmesan cheese and 1 teaspoon Italian seasoning evenly over the surface of the dough.
Cover the skillet again with the kitchen towel and let it rise for another 20 minutes.
While the dough is rising, preheat your oven to 425°F (220°C). Once the focaccia has risen, place the skillet in the oven and bake for about 20-25 minutes, or until the top is golden brown.
Remove the skillet from the oven and let it cool for a few minutes. Cut into wedges and serve warm.