2Combine cake mix, flour, eggs, sugar, milk, canola oil, 1 teaspoon vanilla extract, and baking powder in a large bowl until thoroughly blended; pour into the prepared cake pans.
3Bake in the preheated oven until lightly browned and a toothpick inserted into centers comes out clean, 40 to 50 minutes. Cool cakes in pans about 10 minutes, then remove from pans. Place on wire racks to cool completely.
