
Preheat oven to 350º F (180º C). Line an 8-in (20 cm) round cake pan with parchment paper. Lightly grease with baking spray with flour.
In a large bowl, mix cake mix, water, oil, yogurt, and flour, if using, until everything is well combined. Do not overmix the batter.
Pour batter into prepared pan.
Bake, as directed on the box, or until a toothpick inserted in the center, comes out clean. Cool for 10 minutes before unmolding. Cool completely before frosting.