In the bowl of a stand mixer, using the paddle attachment, mix together 1 1/2 cups flour, salt, and the package of yeast.
While still mixing, slowly pour in the warm water.
Mix well. Stop the mixer and scrape the bowl with a spatula.
In one cup increments, add the remaining 3 cups flour, mixing well between additions.
The dough will come together and release from the paddle attachment.
Cover mixing bowl with a towel, and let rise for 1 hour in a warm place. The dough should double in size.
After the rising period, scrape the dough out of the bowl on to a floured surface. It's helpful to flour your hands as well.
Using as much flour as needed so it doesn't stick, shape the dough into a large disc.
Place the disc in a 12 inch cast iron skillet that has been brushed with olive oil.
Cover with a towel, and let rise again for 30 minutes.
Preheat oven to 400 degrees F.
Lightly brush 2 tablespoons of olive oil on the top of the dough.
Using a sharp knife, slit the dough in 4 places.
Bake for 35 - 40 minutes.
Optional: rub the end of a stick of butter on top of loaf immediately after removing from the oven.