Add butter to a mixing bowl and beat with a hand mixer for 3 minutes.
Add in the sweetened condensed milk and beat for two minutes. (If choosing to add in any extract, add it here.) Scrape down the sides of the bowl and beat again for another minute or two.
Add the flour and baking powder. Beat together until mixed through. (If coosing to add in any mix ins, fold in now. Do not add more than 1 cup!)
Using a cookie scoop, portion the dough into mounds onto a baking sheet. Be sure to leave at least two inches between cookie.)
Bake at 320 degrees for 12 minutes.
Remove from the oven and leave on the pan for five minutes. Then remove from the baking sheet and transfer to a wire cooling rack.
Use a sifter to liberally dust the cookies with the powdered sugar. Allow cookies to fully cool before storing. Makes 22 cookies.