Setting the bowl aside, in the bowl of your mixer (or, in another large bowl, if you have a hand mixer), put all 3 sticks of butter in, and mix until your butter is light and fluffy!
With your mixer running on low, add in the sugar, then beat in the eggs, one at a time, allowing the previous egg to fully incorporate into the mixture before adding the next.
It will look like a curdled mess at this point, but that's okay. With your mixer running on low, slowly add in the flour mix, and mix until this has just come together. This is very important: you don't want to over mix this dough! This will make for a tough cookie! So, seriously, just mix this until the flour and butter mixture have come together.
Cover this with plastic wrap (for some reason, I moved my dough back to the flour bowl. I'm not sure why. You can leave it in the same mixing bowl if you'd like!), and place your dough in the fridge for at least an hour to rest.
After resting, pull your dough out, and preheat your oven to 350*, scoop your dough out into little 1 inch balls, and line them up onto a parchment paper lined baking sheet. Once all of your dough balls are lined up, gently squish down the tops, and bake them for 8-10 minutes. You don't want these to brown, and I have found that 9 minutes in my oven is the perfect time.