1 (18.25 oz) box moist-style dark chocolate cake mix
1 can (12 oz) club soda

Preheat oven to 350° F. Spray a 9-inch by 13-inch baking pan with nonstick spray. In a large bowl, whisk cake mix with soda until smooth. Pour into the pan. Bake until a knife inserted into the center comes out clean, 30 to 35 minutes. Slice and enjoy!