In a large bowl, combine 3 cups of bread flour with your 1/2 cup of active sourdough starter.
Add 2 tablespoons of olive oil and 1 cup of lukewarm water. Mix these together until you form a rough, shaggy dough.
Cover the bowl of bread dough with plastic wrap or a damp towel, and let the dough rest at room temperature for about 30 minutes.
After your dough has rested for the 30 minutes, perform sets of stretches and folds every 30 minutes for the first 2 hours of bulk fermentation.
After your second set of stretches and folds, add 2 teaspoons of salt, 1 cup of sliced jalapeños (adjust according to your heat preference), 8 ounces of cubed cheddar cheese, and 8 ounces of cubed cream cheese to the dough. Fold these ingredients in gently but thoroughly to ensure they're evenly distributed throughout the dough.
After you have completed the stretch and folds and added your inclusions, recover the bowl and let the dough rise until it has roughly doubled in size and shows numerous air bubbles. This could take anywhere from 4 to 6 hours depending on your kitchen temperature.
After your dough has doubled in size turn the dough out onto a lightly floured work surface. Shape it into a round loaf by pulling the edges towards the center, creating surface tension on top of the dough. This tension helps the loaf maintain its shape during the final rise and baking.
Transfer the shaped dough onto a piece of parchment paper. This will make it easier to move into the Dutch oven later.
Allow the shaped dough to proof, covered, for about an hour or until it shows signs of puffiness and has risen slightly. This final proof gives the dough its last chance to ferment and develop flavor before baking.
Preheat your oven and Dutch oven to 450°F (232°C) at least 30 minutes before you plan to bake. This high temperature is crucial for achieving a golden-brown crust.
Place your shaped dough in the refrigerator. It is easier to score if its cold.
Right before baking, use a sharp knife or a razor blade to score the top of your dough. This slash allows the bread to expand in a controlled manner, contributing to the oven spring.
Carefully place the dough, still on the parchment paper, into the preheated Dutch oven. Cover with the lid to trap steam and bake for 20 minutes.
After 20 minutes, remove the lid, lower the oven temperature to 400°F (204°C), and continue to bake for another 25 minutes until the loaf is golden brown and sounds hollow when tapped on the bottom.
Let the loaf cool on a wire rack before slicing to allow the interior to set properly.