Feed your starter 4-6 hours before mixing to ensure it’s active and bubbly.
In a large bowl, mix the flours, water, and starter until combined. Cover and let rest (autolyse) for 30 minutes.
Add honey, salt, and butter (if using). Mix well (by hand or stand mixer) until smooth and slightly elastic (~5-7 mins).
Cover and let rise at room temperature (70-75°F) for 4-6 hours, with 3-4 stretch-and-folds every 30 minutes in the first 2 hours.
Gently shape the dough into a round or oval. Place seam-side up in a floured banneton.
Cover and refrigerate for 8-12 hours (or up to 24 hrs for more sour flavor).
Preheat Dutch oven at 450°F (230°C) for 30 minutes.
Turn dough onto parchment paper, score the top, and bake covered for 25 mins.
Remove lid, reduce heat to 425°F (220°C), and bake 15-20 mins until deep golden.
Let cool on a wire rack at least 1 hour before slicing.
