In the bowl of your stand mixer, combine sourdough discard, water and 510 g flour. Before setting the mixing bowl on the stand mixer, hold the dough hook and stir to combine. Then, attach the bowl and dough hook, and mix these ingredients on speed 2-3 until it turns into a dry ball of dough (about 30-60 seconds.)
Cover with a kitchen towel and let dough rest for 30 minutes, in the meantime measure out the remaining ingredients.
After 30 minutes, add in yeast, salt, sugar, and butter. Continue kneading on stand mixer for 5-10 minutes. Add in flour a tablespoon or two at a time until dough comes together and butter no longer is seen and is fully incorporated.
Kneading is complete when you have a smooth ball of dough that generally swirls along staying attached to the dough hook. Turn off mixer, remove dough and shape into a smooth ball. Gently poke/push the dough in with a finger and watch for it to spring back. If it pops back quickly it is a good sign the dough is done kneading.
Place dough in a greased, clear container, or any container that will be easy to recognize it has doubled in size. I prefer to use this one, with the numbers. Rise until at minimum doubled in size (approximately 1.5-2 hours, depending on how warm your house is.) Instant yeast will make it rise quickly so keep an eye on it! After it has doubled in size, remove to the counter and flatten and stretch the dough with your hands until it makes a large rectangle. Sprinkle shredded cheddar cheese evenly to cover the entire rectangle of dough. From the length of one side, roll dough tightly, tucking and rolling as you go along the entirety of the rectangle (as if you were rolling cinnamon roll dough, you’ll see the spiral once rolling is complete.)
Using a sharp large knife, start a cut 1 inch from the top of the length of the dough, continue cutting along the length of the rolled dough, right down the middle. Cut all the way through so you have two separate pieces of dough, while attached at the top still. Loop one length of the dough over the other and continue wrapping around until you have a beautiful swirled effect that will fit your pan.
I use the 13x4x4 USA pullman loaf pan, but you can use whatever large loaf pan you prefer! Once it is your desired shape and size, tuck the rough ends under and place into a greased loaf pan, cheesy swirl side facing up. Allow to rise for another 45-60 minutes approximately, until once again doubled in size. Watch closely in this final rise, as you will want to preheat your oven when it looks like it is nearly risen.
Place in preheated 350°F oven, and bake for 50-55 minutes, until internal temperature reaches 190°- 210°. Remove to wire rack immediately to allow to cool. Try not to cut the warm bread, I know it is tempting but it is best to let it cool for many reasons. You’re done, you did it!!!