The next morning, preheat your oven to 500°F. Place your Dutch oven inside and allow both to preheat for about 1 hour. (We need the Dutch oven to be very hot to get the best oven spring.)
Once the Dutch oven has been thoroughly preheated, remove your loaf from the fridge. Turn it out, seam-side down, onto a sheet of parchment on a work surface. (The parchment is optional but makes it much easier to move the loaf into the hot Dutch oven.)
Brush off any excess flour from the top of the loaf.
Use a very sharp knife or lame to score the bread. (If the knife is not cutting easily, it can sometimes help to wet it first.)
Once you've scored the dough, carefully lift up the parchment paper and drop the loaf into the hot Dutch oven. Place the lid on top and then place it back into the oven.
Reduce the heat to 450°F and bake the loaf covered for the first 15 minutes.
Remove the lid, reduce the heat to 375°F, and cook for another 20 minutes, or until the loaf is as deep golden brown as you like.
Remove the loaf from the oven and transfer it to a cooling rack once it's cool enough to touch. It's very important to allow the loaf to cool for at least an hour before cutting into it! The bread is still cooking internally and the texture will be very undercooked and gummy if you cut into it too early.