In a large mixing bowl, combine the active sourdough starter and water. Whisk until the starter is mostly dissolved and the mixture appears milky.

Add the bread flour and mix with a dough whisk or sturdy spoon until no dry flour remains. The dough will be shaggy and somewhat sticky.

Cover the bowl and allow the dough to rest for 30 minutes.

This rest period, often called an autolyse, allows the flour to fully hydrate and begins gluten development, making the dough easier to work with later.

After the 30-minute rest, sprinkle the salt evenly over the dough.

Using damp hands, gently press the salt into the dough. Fold and squeeze the dough several times until the salt is fully incorporated.

The dough may feel slippery at first, but it will smooth out as the salt is absorbed.

Perform 3–4 sets of stretch and folds, spacing each set approximately 30 minutes apart.

For each set:

Wet your hands to prevent sticking.

Grab one side of the dough.

Stretch it upward until you feel resistance.

Fold it over toward the center.

Rotate the bowl one-quarter turn and repeat.

Continue until you have completed four stretches and folds, making one full rotation around the bowl.

With each set, you'll notice the dough becoming smoother, stronger, and more elastic.

After completing the stretch and folds, cover the bowl and allow the dough to continue fermenting at room temperature.

Depending on the temperature of your kitchen, bulk fermentation typically takes 4–6 hours.

The dough is ready when:

It has increased in volume by approximately 50–75%.

The surface appears slightly domed.

Small bubbles are visible throughout the dough and along the sides of the bowl.

The dough jiggles slightly when the bowl is shaken.

It feels light and airy rather than dense.

Avoid allowing the dough to double completely, as over-proofing can result in a weaker final loaf.

Lightly flour your work surface with rice flour and gently turn the dough out onto the counter.

Using your fingertips, carefully stretch the dough into a large rectangle. Take care not to press out all of the air developed during fermentation.

In a small bowl, combine the chocolate chips, crushed graham crackers, and mini marshmallows.

Sprinkle a little over half of the filling mixture evenly across the surface of the rectangle.

Next, fold the top third of the dough down toward the center.

Fold the bottom third up over the top fold, creating a letter-style fold.

Sprinkle about half of the remaining filling mixture over the newly folded surface.

Fold the dough in half once more to create one long strip of dough.

Top the strip with the remaining filling mixture.

Starting at one end, gently roll the dough into a tight spiral, enclosing the filling as you roll.

Once rolled, use your hands to shape the dough into a boule.

To create surface tension, gently cup your hands around the dough and pull it toward you while rotating it slightly. Repeat several times until the surface becomes smooth and taut.

Be gentle during shaping, as the chocolate chips and marshmallows can tear through the dough if handled too aggressively.

Transfer the shaped boule seam-side up into a banneton dusted generously with rice flour.

When ready to bake, place a Dutch oven with its lid into the oven.

Preheat to 450°F (232°C) for at least 30–60 minutes to ensure the Dutch oven is thoroughly heated.

Remove the dough from the refrigerator.

Turn it out onto a piece of parchment paper or a bread sling.

Using a bread lame or sharp knife, score the top of the loaf.

Carefully transfer the dough into the hot Dutch oven.

Cover with the lid and bake for 30 minutes.

Remove the lid and continue baking for an additional 15–20 minutes, or until the crust is a deep golden brown and the internal temperature reaches 205°F (96°C).

Carefully remove the loaf from the Dutch oven and transfer it to a wire rack.

Allow the bread to cool completely before slicing.

Although it may be tempting to cut into it immediately, cooling allows the crumb to finish setting and prevents a gummy texture.