In a large mixing bowl, beat the softened butter and 1.5 cups sugar together for 3-4 minutes until the mixture is light, fluffy, and pale in color. This creaming process incorporates air into the butter, which helps the cookies rise and develop a tender crumb. Scrape down the bowl occasionally to ensure even mixing.

Add the room temperature eggs one at a time to the creamed mixture, beating well after each addition. Room temperature eggs blend more smoothly into the butter and help create a homogeneous dough. Make sure each egg is fully incorporated before adding the next one.

In a separate bowl, whisk together the sifted flour, cream of tartar, baking soda, and salt. Gently fold this dry mixture into the wet ingredients until just combined—overmixing will toughen the cookies. The cream of tartar reacts with the baking soda to create lift and give these cookies their characteristic slightly chewy texture with crispy edges. Once combined, cover the dough and refrigerate for at least 1 hour, or up to overnight, which allows the flavors to develop and makes the dough easier to handle.

While the dough chills, preheat your oven to 350°F and prepare the cinnamon sugar coating by mixing the 3 tablespoons sugar with 2 teaspoons of freshly ground cinnamon in a shallow bowl. I find that freshly grinding whole cinnamon sticks gives a more vibrant, complex flavor compared to pre-ground cinnamon, which really makes these cookies special. Have this mixture ready for the next step.

Remove the chilled dough from the refrigerator and roll it into 1-inch balls. Working quickly (the dough can soften at room temperature), roll each ball in the cinnamon sugar coating until evenly covered, then place on parchment-lined baking sheets about 2 inches apart. The cookies will spread slightly as they bake, so proper spacing is important.

Bake the cookies for 9-11 minutes at 350°F, until the edges are lightly golden but the centers still look slightly underdone—this is the key to getting that perfect chewy center with crispy edges. Remove from the oven and let the cookies cool on the baking sheet for 2-3 minutes, then transfer to a wire rack to cool completely. I like to let them cool slightly on the sheet first because it helps them set without becoming too crispy.