I like the Norwich sourdough recipe and have had success with proofing in the refrigerator. I use freshly milled hard white and rye flours, add 80g more water to the recipe, and a 100% hydration levain I build from KA white flour. When I remove the proofing baskets from the refrigerator the dough is over the top of the banneton. Everything is great until I place the boule on the Emile Henry cloche base when my dough deflates. I am new to bread baking and sourdough and welcome any and all advice. Thanks!
First, what a gorgeous loaf. While I am an expert at overproofing, in general, if it collapses in the oven during the bake, it is overproofed. I have read various suggestions, but generally , you want it in the oven and baking before it reaches full proof. I can't give you much help in how to determine ideal proofing stage, but suggest you keep trying, each tim make the same size loaf, and watch the volume, and each try put in the oven when it is a little smaller than the previous try, until you get some oven spring.
What % whole grain is the recipe?
How do you prepare the cloche ? oven preheat time?
The bread looks great from the top!