In a large mixing bowl, beat butter and sugars until creamy (1-2 minutes).
Add eggs, vanilla and milk and beat for an additional two minutes.
Add flour, baking powder, and salt and beat another two minutes.
Drop cookie dough on a parchment lined baking sheet. Tip: I typically load all the dough balls on to a baking sheet and then pop in the freezer for about 20-30 minutes. It seems to make the dough hold up better and not spread as much during baking. If you're in a rush, don't worry about freezing. They'll still be delish!
After the dough has firmed up in the freezer, pull out the amount that you want to bake and bake at 375 for 12-14 minutes (if using completely frozen dough, you may need to add a minute or two to your baking time).
Pop the leftover dough balls in a Ziplock bag and put back in the freezer. When baking frozen dough, you may need to add a couple more minutes to your baking time. I've made two batches from the frozen dough, and I have only had to add one minute so keep an eye on it!