Place one cup of flour in the bowl of a stand mixer. Add sugar, salt, and yeast, mix to combine.
Add water and butter to a measuring cup. Microwave for approximately 30 seconds and pour over the other ingredients in the bowl. Add sourdough starter, then mix on medium until combined.
Continue to add flour, one half cup at a time. Mix after each addition. The dough should to be slightly sticky. Knead for five minutes.
Add cubed cheese and sliced jalapeños to the bowl, then mix on low.
Remove the dough and shape into a ball. Place in a greased bowl, turning once to oil the surface. Cover with plastic wrap and allow to rise for 2 hours or until doubled in volume.
Punch down the dough, and form into a loaf. Place on a baking stone, or a baking tray that's covered with a silicone mat or parchment paper. Cover the dough loosely with a tea towel and place it in a warm location for one hour.
After an hour has elapsed, preheat the oven to 375 degrees F. When the oven is ready, make a few slits into the top of the dough using a razor blade.
Bake for 30 to 35 minutes, or until nicely browned. Allow the jalapeno cheddar sourdough bread to cool completely before slicing it.