Preheat the Oven: Set the oven to 375°F (190°C).
Mix the Dough: Stir together cake mix, cooled butter, eggs, and lemon zest until a soft dough forms.
Make Coating: Combine powdered sugar and cornstarch in a shallow dish using a fork.
Shape the Cookies: Roll 1-inch dough balls in the sugar mixture and place them 2 inches apart on ungreased baking sheets.
Bake: Bake one sheet at a time for 9–11 minutes, until set in the center.
Cool Completely: Cool on the sheet for 1 minute, then move to a wire rack to finish cooling for about 15 minutes.