I am using the no-fail recipe (which I absolutely love) and I was wondering if I added a Tbsp of milk would the cookies spread too much?

I dont think they would?! Is it a sugar recipe? Why do u want to add milk?

Because, it seems like my KA mixer has a tough time mixing the dough and I wanted to add a little liquid. Why, what is going to happen if I add the milk?

no problem at all...I've added up to 1/4 cup of milk per recipe.

You can also take out 1/3 cup of the flour too.