Instructions

Heat oven to 375°F. In a large bowl, mix together butter and ⅔ cup sugar with an electric mixer on low speed until combined. Increase speed to medium-high and mix until creamed together and fluffy. Mix in the milk, vanilla, and apple cider vinegar on low speed until well blended.

Sift the flour, 1¼ teaspoon cinnamon, cream of tartar, baking soda, and salt into the butter mixture. With a wooden spoon, stir the dry ingredients into the butter mixture until a crumbly dough forms.

In a small bowl, mix together 3 Tablespoons sugar and 1 teaspoon cinnamon. Press and roll the dough into 24 balls. Roll each dough ball into cinnamon and sugar mixture and. Place 2-inches apart on parchment-lined cookie sheets. Flatten each cookie slightly with the bottom of a glass.

Bake 6 to 8 minutes or until cookies are just set on the edges; they will crisp up as they cool. Remove from the oven, cool 1 minute on the cookie sheet. Move to a cooling rack to cool completely.