If you're planning to bake right away, then preheat the oven to 350°F/180°C.
In a bowl, whisk together the flour, baking powder, and salt until well combined. Set aside.
In the bowl of a stand mixer, cream together the butter and sugar (here's how to do it). Add the egg, vanilla extract and milk, and beat again until well combined.
Add the dry ingredients to the wet ingredients, and mix again until just combined. Do not overmix the cookie dough.
Divide into 4 portions, cover with plastic wrap, and chill or freeze until you're ready to use or start shaping and baking!
When ready to bake, if making small 1 tablespoon size cookies, bake at 350°F/180°C until the bottom of the cookie is golden brown (about 8 minutes).
Notes
You can easily halve the recipe if you like, or double it.
I divide the dough into 4 portions, and then divide each into 2 portions to make 8 types of cookies.
Yield: The total weight of the dough is around 5 pounds (2.2kg), and makes over 140 small cookies.
I used this cookie dough to make: Soft chocolate chip cookies, M&M cookies, sprinkle cookies, snickerdoodles, hidden kiss cookies, jam thumbprints, Iced cookies, and cut-out sugar cookies