You definitely need to scale up the dark malts too if you are upping the abv. I made an 8 % version and I uswd more dark malt but it came out not as dark as I wanted
i made a batch of this. went from 1.066 to 1.020 using nottingham yeast. i will be bottling in a week or so. i just added two vanilla beans i had soaking in some vodka since brew day last sunday. i hope it turns out well! it is my first porter i've made. thanks for the recipe.