Since I know many folks don't fancy themselves bakers, I've decided to share some examples on making baking mixes vegan. Clearly the mix itself needs to be free of dairy and eggs, which you can determine by checking the ingredients on the label.
Cake has a different texture from brownies, but I still favor substituting the egg with applesauce. It is a familiar item anyone could find at any grocery store, including Trader Joe's. The cake itself called for butter or oil, and I opted for oil.
A topping mix is included, and all you needed to do is use Earth Balance Buttery Sticks or Natural Spread. These both can be found at Trader Joe's.
The last modification I made was to add 2 teaspoons of vinegar. You won't be able to taste it afterwards, I promise! It helps the cake to rise.
Here is the list of ingredients for the cake mix:
2/3 cup almond, soy, coconut, or hemp milk
6 Tbsp. oil
2/3 cup applesauce
2 tsp. vinegar
3 1/2 Tbsp. Earth Balance Buttery Sticks or Natural Spread