Preheat oven to 375 degrees F. Line with parchment paper or a silicone baking mat. Blend sugar and cinnamon in a bowl and set aside.
Combine cake mix, eggs, oil, and 1 tablespoon of cinnamon sugar in the bowl of a stand mixer. Shape dough into 1 to 1 1/4-inch balls (I used a 1 1/4-inch cookie scoop) and roll in the remaining cinnamon sugar mixture. Place onto prepared cookie sheet. Flatten cookies, gently, with the bottom of a flat glass.
Bake for 8 to 9 minutes or until set. Cool cookies for 1 minute before removing them to a cooling rack to cool completely. Store in an airtight container for up to 4 days.