Preheat the oven to 375 degrees F (190 degrees C).

Combine the 1 (15.25 ounce) box Duncan Hines red velvet cake mix, 6 tablespoons unsalted butter (melted and cooled), 2 large eggs, and 1 teaspoon lemon zest in a large mixing bowl. Mix by hand until all ingredients are well blended and a soft dough forms.

Whisk the 1 cup powdered sugar and 1 teaspoon cornstarch together with a fork in a shallow dish until thoroughly blended. This will be your coating mixture.

Form the prepared dough into 1-inch balls. Roll each dough ball generously in the powdered sugar mixture, ensuring they are fully coated. Place the coated dough balls about 2 inches apart onto cool, ungreased baking sheets.

Bake one sheet at a time in the center of the preheated oven until the cookies are set, typically 9 to 11 minutes.

Cool the baked cookies on the baking sheet for 1 minute, then transfer them to a wire rack to cool completely, which will take about 15 more minutes. Repeat this process to bake the remaining cookie dough.