Sweet Changes

I need to make an apple cake for someone - and because I just made a caramel apple cake for the first time, it led me to the next idea of making a caramel apple cake. Though I technically could make my own caramel, I will try that out another time. I found a place where i can buy caramel bits in bulk. I am going to create the caramel apple cake recipe. So far, it will include caramel bits, chopped nuts, chopped apples, and apple sauce. For the first round, i will use butter and eggs - Because the person whom I am making it for has no interest in vegetarianism. The second round i will use vegan substitutes...extra baking powder and soy milk in place of eggs. And maybe just use some oil for the butter. Would avocados work in lieu of butter?