Sorry you had them spread too much, 1/2 TBS (or 1.5 tsp of vanilla) isn’t a lot (only 1/2 tsp more than the original recipe from the Quaker oats box) and definitely not too extra liquid to cause a huge spread. Everything else is the same as their original recipe (except 2 cups butterscotch instead of 1 cup raisins). Did you use extra large eggs? Or do you live in a high altitude?

Sorry your cookies spread more than you wanted, I’ve used this base cookie recipe for these butterscotch cookies, cranberry cookies, chocolate chip, etc and made it over a dozen times without them spreading. If you’re having issues it’s likely that you mis-measured something or your butter was too soft. I would try chilling the cookie dough in the fridge for at least an hour and see if that helps them keep their shape better. If your dough is extra sticky I’m guessing something was measured wrong, and I’d try adding in a little more flour, then chilling the dough. Let me know if you have any other questions!

You should be fine subbing a 1:1 flour