I have recently tried baking 1.8 kilo. boules following Forkish's recipe. (p.172 in Flour, Water, Salt, Yeast)However, the center of my loaves is underbaked. The crust is quite crisp and oven spring is decent. Any suggestions? Or maybe I just need to bake the loaf another 10-15 minutes...
Keep baking and watch the crust. Enjoy!
Bake at a lower temperature. Or reduce the temperature after the oven spring is finished. You want to prevent the crust from over-cooking before enough heat has reached the inside to finish baking it.
TomP