Combine yeast, ¼ cup bread flour, sugar or honey, and warm water.
“Proof” until the yeasts are rehydrated and bubbly, producing a yeasty fragrance, about 20 minutes. If you prefer, you may use a 1 1/2 cups sourdough starter in place of the previous sponge and skip to step two.
Add butter, chiles, chili flakes, salt, eggs and yolk to the yeast sponge and combine thoroughly.
In a stand mixer fitted with a dough hook, start adding flour in ½ cup increments until it is a cohesive ball that pulls away from the sides of the bowl, but is still slightly sticky.
Turn dough out onto a lightly floured surface and knead for 2-3 minutes. The dough should be smooth, soft and slightly sticky.
Place in a greased bowl and cover with plastic wrap and allow to rise in a warm spot until doubled in size, about 1-2 hours.
After the first rise, turn dough out onto a well floured surface. Work into a coarse rectangle, then roll to approximately 12” wide by 18” long.
Sprinkle surface with the cubed cheddar. Tightly roll the cheesed studded dough lengthwise to form a long log. Pinch the ends and roll log back and forth a few times to seal seams.
Coil log, from center out, in the bottom of a greased cast iron skillet. Cover with plastic wrap and allow to rise onto doubled in size, about an hour.
Preheat oven to 350 degrees.
After second rise, remove plastic wrap, and brush with a beaten egg if desired.
Bake for 50 minutes, covering loosely with aluminum foil after about 25 minutes to avoided overly browning.
Remove for pan and slice into large wedges, slather with butter and enjoy.