Mix together flours, salt, yeast, and rosemary in a large bowl.
Add water and mix until combined.
Cover bowl with plastic wrap.
Let dough sit on counter for 12-24 hours.
Preheat oven and ceramic soup pot to 450.
Sprinkle flour on top of dough and dump out onto parchment paper.
Form dough into a ball shape on the parchment paper and carefully place in preheated ceramic pot.
Cook in a ceramic pan covered for 30 minutes.
Uncover and cook for an additional 10-15 minutes.
Let cool for at least 15 minutes before slicing.