Activate the Yeast: In a small bowl, combine the warm water and active dry yeast. Stir gently to dissolve the yeast. Allow the mixture to sit for about 5 minutes, until it becomes foamy and fragrant, signaling the yeast is active.
Mix the Dry Ingredients: In a large mixing bowl, whisk together the all-purpose flour and salt until evenly combined.
Form the Dough: Pour the yeast mixture into the flour mixture. Using a wooden spoon, stir until the dough comes together in a slightly sticky ball. If the dough sticks excessively to the bowl, gradually add 2-3 tablespoons more flour. If it feels too dry, add 1 tablespoon more water.
First Rise: Cover the bowl with a clean kitchen towel or plastic wrap. Let the dough rest in a warm spot until it roughly doubles in size, about 1½ to 2 hours.
Fold the Dough: Turn the dough onto a floured surface. Gently flatten it into a round disc. Fold the dough into thirds, like folding a letter. Rotate 90 degrees and repeat the fold. This technique strengthens the dough’s gluten.
Second Rise: Place the folded dough back into the bowl, cover again, and let it rise for another 1 to 1½ hours, until doubled.
Prepare the Jalapeños: On a cutting board, slice 4 to 5 thin rounds from one jalapeño; set these aside for topping. Remove seeds and membranes from the remaining jalapeños and dice them finely.
Incorporate Jalapeños and Cheese: Place the diced jalapeños and cubed cheddar on top of the dough. Fold and gently knead the dough several times on the floured surface to evenly distribute the spicy and cheesy additions.
Shape the Dough Ball: Lightly dust a piece of parchment paper with cornmeal. Shape the dough into a tight ball, seam side down, and place it on the parchment.
Final Rest: Cover the dough loosely and let it rest for 30 to 40 minutes to relax before baking.
Preheat Oven and Dutch Oven: Preheat your oven to 450°F (232°C). Place a covered Dutch oven inside to heat along with the oven.
Score and Top Dough: Carefully remove the hot Dutch oven from the oven. Using a sharp knife, make four shallow cuts in a square pattern atop the dough (each about ½ inch deep). Brush the dough lightly with water if needed. Sprinkle shredded cheddar cheese and reserved jalapeño slices evenly on top.
Bake the Bread: Using the parchment, transfer the dough ball into the preheated Dutch oven. Cover with the lid and bake for 45 minutes.
Brown the Crust: Remove the lid and bake uncovered for an additional 5 to 10 minutes, until the crust is a deep golden brown and the internal temperature reaches about 200°F (93°C).
Cool Before Serving: Remove the bread from the Dutch oven and transfer to a wire rack. Allow to cool completely before slicing to preserve texture and flavor.