In a large bowl, whisk the starter, water, and peanut butter until mostly combined. Stir in the honey if using, then add the flour and salt. Mix until no dry flour remains. Cover and rest 30 minutes.

Cover the bowl tightly and let ferment at room temperature for 8 to 12 hours, until doubled and bubbly.

Turn the dough onto a lightly floured surface and shape into a round. Rest 20 minutes, then do a final shape and place seam side up in a floured banneton.

Cover and proof at room temperature for 1 to 2 hours, until puffy and a poke springs back slowly. Or refrigerate overnight, then bring out 30 minutes before baking.

Preheat a Dutch oven in a 450°F (230°C) oven for at least 30 minutes. Invert the dough onto parchment, score the top, and lower into the hot pot. Bake covered 30 minutes, then uncovered 15 to 20 minutes until deep golden brown and the center reads 205°F to 210°F (96°C to 99°C). Cool completely on a wire rack before slicing.