Put one cup of water in a small saucepan and heat to boiling.
Remove from heat and add honey and butter. Stir to dissolve.
Then stir in rolled oats. Just like making porridge. Set aside to cool slightly.
Pour the sourdough starter into a large mixing bowl or the bowl of a stand mixer. Add the remaining water and stir till thoroughly mixed.
Add the egg, the honey and cooked oats mixture, the salt, the yeast (if using), and 2 cups of flour. Mix well.
Add the remaining flour a little at a time until you've got a soft dough.
Scrape the dough out onto a lightly floured work surface and knead for 5 to 8 minutes until the dough is smooth and no longer sticky.
Or attach the dough hook and knead in the stand mixer for 8 minutes.
Form the dough into a ball and place in a greased bowl, turning to oil the top.
You can use butter, coconut oil, or olive oil to grease your bowl.
Cover with a damp bread cloth or plastic wrap and put in a warm place to rise till doubled. Yeast added method, 1 to 1 1/2 hours. Sourdough only method, 4 to 6 hours.
Butter 2 bread pans. Or you can use a banneton or 2 depending on how big they are. Make sure the banneton baskets or liners are well floured.
Once the dough has doubled, turn it out onto a slightly floured surface. Using a bench knife, or other sharp knife, divide the dough in half.
Form each half into a loaf. Place seam side down in the loaf pans, or seam side up in the bannetons.
Cover again and let it rise again until doubled. Yeast method, 45 minutes to and hour. Sourdough only method, 1 to 3 hours.
About 20 minutes before your honey oat sourdough bread is ready to bake, preheat your oven to 350°F.
If you used bannetons, turn the loaves out onto a greased or parchment covered baking sheet.
Right before baking, brush melted butter on the top of the loaves. You can sprinkle them with a little bit of rolled oats if you want to be a little fancy.
With a sharp knife or bakers lame, make a slash down the center of the loaf lengthwise.
Now, pop those sandwich loaves in the preheated oven and bake for 40 to 45 minutes, until lightly browned.
Remove from the pans. If the crust is not as dark as you would like, you can return them to the oven for about 5 more minutes.
If you have any remaining melted butter, brush that on the top of your loaf now.
Put on a wire cooling rack to cool off.
Allow to cool for at least 20 minutes before slicing.