Sift or whisk 3 1/2 cups all-purpose flour, 1 tsp cream of tartar, 1 tsp baking soda and 1/4 tsp salt in a medium sized mixing bowl.
In a large mixing bowl, cream the 1 cup unsalted butter, softened and 2 cups brown sugar, packed until light, about 2 minutes.
Add in 2 large eggs, one at a time followed by 1 tsp vanilla extract.
Add in 2 tbsp cream or milk.
Gently add in dry ingredients, in three separate batches. Fold in 1 cup nuts, finely chopped (such as walnuts or pecans).
Divide dough in half. Place each half of dough on to parchment paper, waxed paper or plastic wrap. Shape into a log, about 2 inches in diameter.
Chill dough minimum 1 hour.
Slice 1/4" thick and bake at 375°F for 8-10 minutes*. Cool on wire rack.