VERY IMPORTANT: Remove 1 cup of starter mixture from the bowl and put it back in the fridge. (This is now freshly fed starter that won't need fed again until you make bread, or something else, in a week or two or three).
Add the remaining hot water, sweetener, oil or butter, and salt. Stir to combine.
Add the whole wheat or spelt flour, two cups at a time. Stir until it becomes too thick, then begin kneading to mix the flour in.
Add flour until the dough begins to pull away from the side of the bowl and is less sticky. A little sticky is okay. It will become less sticky as it rises. (Don't add too much flour or you will get a dense, heavy loaf. Error on the side of too little flour rather than too much.)
Knead for about 5 minutes. Sometime I knead more, sometimes less. It doesn't seem to matter as much with this recipe.
Cover the bowl with a wet towel or plastic wrap and leave in a warm, draft free room place to rise. Let rise about 2 hours, or until doubled in size.
Punch the dough down, flip it, and punch 2 more times. Cover and let rise again for about 1 hour or until nearly doubled.
Coat 2 bread loaf pans with oil. Coat your hands and counter with oil. (Don't use gluten-containing flour!) Punch down your dough and divide into 2 loaves. Shape them into rectangles a little smaller than your bread pans (they will rise up quite a bit and more than fill the pan). Place in the bread pans, cover with plastic or a wet towel, and let rise about 1 hour, or until 1/2 inch above your bread pan.
Bake at 400 degrees F for 35-40 minutes until nicely browned on top.
Spread butter over the tops of the hot loaves and let cool on the counter. I like to remove mine from the pan after they've cooled and let them sit on the counter upside down for a lit while to let moisture escape from the bottoms of the loaves before wrapping them in plastic. They will store at room temperature for at least a week. Or store in the freezer.