Preparation Steps

• In a large bowl, cream together the softened butter, granulated sugar, and light brown sugar until light and fluffy.
• Beat in the egg yolk and vanilla extract until well combined.
• In a separate medium bowl, whisk together the all-purpose flour, cream of tartar, baking soda, and salt.
• Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.
• Cover the bowl with plastic wrap and refrigerate the cookie dough for at least 30 minutes to firm up.
• While the dough is chilling, prepare the cinnamon sugar coating by combining the granulated sugar and ground cinnamon in a shallow dish.
• Once the dough is firm enough to handle, roll it into small balls, about 1-inch in diameter.
• Roll each ball in the cinnamon sugar mixture until evenly coated.
• Place the coated truffles on a baking sheet lined with parchment paper.
• Refrigerate the truffles for another 15-20 minutes to set, or until firm.
• Serve immediately or store in an airtight container in the refrigerator.