For the dough:. In a bowl, sift together the flour, baking soda, baking powder and cream of tartar. Set aside.
In a separate bowl, cream the butter and sugar until fluffy. Add the eggs, milk and vanilla. Mix well.
Stir in the dry ingredients. Stir until just combined.
Cover bowl (or remove dough from bowl and wrap in plastic wrap) and chill for 2+ hours. You can chill for up to 24 hours if you have time.
When ready to bake, Preheat the oven to 350 degrees. Form the dough into 1 inch balls. Mix cinnamon and sugar in a small bowl and roll each ball of dough through the cinnamon and sugar mixture to coat well.
Place on a greased baking sheet or a cookie sheet covered with wax paper or silicone baking mat.
Bake 8-9 minutes. Do not overbake. Allow to cool on baking sheet for at least ten minutes before transferring to a wire cooling rack.