In the bowl of stand mixer (or large mixing bowl) add lukewarm water. Add yeast and salt, mix to combine. Add flour. Mix with paddle (or wooden spoon) on low until combined.
Switch to dough hook. Add crumbled bacon, scallions, and parmesan cheese. Mix on medium speed (or by hand) for 5 minutes.
Scrape dough into large (4-6 qt) container with lid. Cover and let sit in warm area on counter for at least 2 hours, or until doubled in size. At this point dough may be refrigerated for up to 2 weeks.
When ready to bake, preheat oven to 450F. Divide dough in half by hand. Flour a clean surface and your hands. Form a boule by shaping the dough into a ball and repeatedly stretching the edges down and underneath. Sprinkle the dough with flour if needed to prevent sticking. This may be repeated if baking both loaves at once, or the other half may be saved for up to 2 weeks.
Once shaped into a ball, dust with flour and allow it to rest, covered with a dish towel, for 45 minutes (or 20 minutes if starting with room temperature rather than refrigerated dough)
While dough is resting, place an empty, covered cast iron Dutch oven into the preheated oven. Allow it to heat for 20 min prior to baking bread.
Score top of bread boule with a serrated knife to form an "x". Place into preheated cast iron pot, and place the pot back into the 450 oven, covered.
Bake 25 min covered. Remove lid and bake an additional 20 min uncovered. Let bread cool on baking rack for a minimum of 30 min before slicing.
This recipe makes two loaves of bread as is. It can be easily halved or doubled.