Which ingredient is NOT found in the warm butter cake recipe?

The correct ingredient that is not found in the warm butter cake recipe is milk. In many butter cake recipes, sour cream or cream cheese is often included to add moisture and richness, contributing to the cake's dense and buttery texture. All-purpose flour is essential for providing structure to the cake. While these other ingredients are commonly used, milk is not a necessary component and in some recipes is replaced by sour cream or cream cheese, which can enhance the flavor and texture without the use of milk. This alternative addition allows the cake to retain moisture and achieve a unique taste profile that complements the butter.