Par-baked bread, short for partially baked bread, is a process of cooking the bread through without finishing it, removing it from the oven for a time to cool, then completing the baking at a later time. Many retail stores and bakeries, including La Brea Bakery, use this process to bake large quantities of bread at another location, then finish the bread on site, supplying the customers with warm, out-of-the-oven loaves.
Find a basic bread recipe. King Arthur Flour always has good reliable recipes on the back of its 5 lb. bags. For bread, there are four ingredients you'll definitely need--flour, yeast, water, salt--and a number of ingredients you might need, depending on the type of bread: honey, milk, eggs, dried fruit, molasses, whole grains, etc. Get all of your ingredients out and measure them all out, by weight. You'll need a scale.
Pour your liquids into a bowl. If the recipe includes a sweetener like honey or sugar, add it to the liquid. Pour your flour on top of the water. Add the instant yeast and salt to the flour, mixing together these dried ingredients without fully incorporating the water. Then mix everything together with your hands, making sure to hydrate all of the flour. Don't worry about kneading.
Throw convention out of the window. Once it's all incorporated, stop everything. Clean your hands, cover the bowl with a towel and go watch a 30-minute television show. If you don't have cable, entertain yourself for 30 minutes without touching the dough. Don't touch the dough!
Wait 30 minutes, then take a bit of warm water and get your hands and work surface damp. Pour out the dough and fold it three times. Stretch the end of the dough toward you, then fold it away from you. Rotate 90 degrees and repeat. Then repeat. Now you should have a nice tight ball. Put it back in the bowl and continue with the proofing process.
Bake as usual, but cut the time by 1/4. So if the recipe calls for an hour, bake it 45 minutes. But the time is just an estimate. The goal is to completely bake the bread internally to a temperature of 185 degrees without browning it at all on the outside. Once it's reached that internal temp, take it out.
Let the bread cool to room temperature. This will take longer than you think, at least 2 hours. Once it's cool, put it in a plastic bag until later. If you're baking it the same day, you can just refrigerate or keep it out at room temp. If you're saving it for a while later, freeze it.
Finish baking the bread. Preheat the oven with the cast-iron skillet inside. Boil 2 cups of water. When you put the bread in, pour the boiling water into the skillet. This steam will keep the bread from drying out. Bake for 20 minutes or so, until the loaf turns brown. Ideally, the spectrum will vary from light to dark, almost black. When the loaf achieves this color, take it out, and enjoy!