Mix in vanilla and eggs. Beat on medium speed until incorporated.
In a separate bowl, mix together 6 cups of flour, baking powder, baking soda and salt.
Add flour mixture alternately with milk. Mix at low speed just until all flour and milk are mixed into the butter mixture. Do not over mix. If the mixture feels too sticky, fold in another 1/4-1/2 cup of flour. I try to add as little extra flour as possible to keep the dough soft but not sticky!
You may refrigerate at this point, overnight or up to three days before baking. It is best to refrigerate covered dough for at least 1-2 hours.
Roll out on floured surface in batches about 1/4 inch thick*. Cut with cookie cutters into desired shapes.
Place immediately on ungreased baking sheets about one inch apart.
Bake at 350 degrees for about 12 minutes or until lightly golden on edges.
Yields about 35-40 3x5 inch cookies
Beat butter until soft. Add 3 cups of powdered sugar. Continue mixing on low.
Add salt and vanilla.
Add 2 more cups of the powdered sugar. Mix until smooth.
Add the milk a tablespoon at a time, along with the last cup of powdered sugar.
Scrape down sides of bowl, and mix until all ingredients are incorporated and smooth. Add food coloring if desired.
Yields enough frosting for about four dozen cookies* see recipe notes.