*Standard cake mixes have fewer ounces than they did in the past. Lately I’ve been using Betty Crocker’s Betty’s Original Recipe Scratch Cake Mix – Golden Yellow. It is 19.2 oz. and works wonderfully in this recipe.
Alternatively, you can buy two boxes of cake mix and add 6 Tbls. of additional cake mix to increase the amount.
Another alternative, make a cake mix upsizer by combining 1 1/2 C. flour, 1 C. sugar, 2. tsp. baking powder, 1/4 tsp. baking soda. Use 6 Tbls. to boxed cake mix. Store remaining upsizer mixture in jar.
Find it online: https://www.imbored-letsgo.com/black-russian-cake/