Cream butter and sugar in the bowl of a stand mixer fitted with the paddle attachment until light and fluffy. Add egg and beat well.
Add milk and vanilla and beat well.
Whisk together flour, baking powder and salt. Reduce mixer to low and add dry ingredients in three additions, waiting until almost all the flour has been incorporated before adding the next.
Scoop with a large cookie scoop or roll in to balls about ¼ cup size. Chill dough before baking.
Place on cookie sheet lined with parchment paper and bake in preheated oven 10-12 minutes until the edges are a nice golden brown, the centers have puffed and the surface looks matte not shiny.
Notes
Yield: 13, 45g cookies
Cool completely. Store in a sealed container at room temperature for up to 7 days. They will gradually lose their moisture.