As an experiment, you might try adding a bit of oatmeal stout to a portion of the cookie dough. I know your oatmeal stout won't be ready for this batch, but you could use a storebought one just to see if it would work. I like MMB's idea on toasting your oats, you could try adding some toasted oats to the cookie dough too, might be tasty. I'll bet oatmeal cookies go well enough with an oatmeal stout. Regards, GF.