Add yeast and one cup of the warm water into a small bowl and set aside.

Add the salt and the flours in a large bowl and whisk together.

Add one cup of bubbly sourdough starter to the dry flour/salt mixture. The sourdough should be bubbly and the consistency of melted marshmallows to be ready to use.

Add the yeast and water mixture you had set aside to the flour/sourdough mixture.

Add an additional 1/2 cup of warm water to the mixture and stir with a wooden spoon.

Dump the mixture onto a floured work surface such as a counter or wooden cutting board and knead for about 5 minutes

Try not to add too much flour to the mixture, add just enough to keep your hands from sticking. This will keep the bread light and airy. You can also try wetting your hands to keep the dough from sticking to them.

Add butter chunks in thirds and knead into the dough.

When the dough is smooth and satiny, just barely sticking to the work surface, place the dough in a large buttered bowl or buttered dutch oven.

If you're using a dutch oven put the lid on. If you are using a large bowl wet a hand towel until just damp and place over the top. Put the dough in a warm place to rise such in a warm windowsill, on the 'proof' setting in your oven, or near a fireplace.

Let the dough rise for about two hours or until the dough sinks when you poke it with a finger.

If you're cooking a large round loaf, push the dough flat and fold it back under itself forming a rough ball with the seams underneath. Cover again with the lid in the dutch oven or place the dough on a cookie tray and dampen the towel again and cover. If using bread pans, split the dough in half and use a rolling pin to roll the dough into a rectangle about 2/3 the width of the bread pan. With your hands roll the dough from short end to short end into a log. Pinch the ends of the log together and slightly tuck under the dough log. Place the dough seem side down in the pan. Repeat with the second half of the dough. Cover with a moist cloth or plastic wrap. Let rise in a warm place for one hour.

Preheat the oven to 400 degrees Fahrenheit.

When heated put the bread in the oven and use a spray bottle to mist the bread with water. Bake the bread in the same dutch oven, cookie sheet, or bread pans for 30 minutes or until the bread makes a hollow sound when you tap it with the handle of a bread knife.

Take the bread out of the oven and let the bread sit for 15 minutes before cutting into it. Enjoy!