If you have all your ingredients out with the plan to make a batch of cupcakes only to find out you are short an egg or your bottle of oil is empty, your refrigerator may hold the ideal substitute. Mayonnaise, made from eggs, oil and a bit of vinegar, makes an excellent alternative for the oil and eggs in your recipe, with a few considerations. When used with chocolate cake mixes or recipes, the hint of vinegar enhances the chocolate flavor as well.
Preheat your oven to the temperature your cake mix or cupcake recipe recommends. Fill your cupcake pan with cupcake liners and set aside.
Place your dry ingredients in a bowl. Measure your mayonnaise to match the amount of oil your recipe calls for. Mix these ingredients together. Typically, your recipe will also include water or milk. You may need to adjust the recommended amount when using mayonnaise. Slowly add the water or milk to the mixing bowl until you reach cake batter consistency. Mix all the ingredients together as directed and fill your cupcake liners 1/2 to 2/3 full.
Place your cupcake pan in the oven and bake as directed. To test for doneness, insert a toothpick into the center of one cupcake. Cooking is complete when the toothpick comes out clean. Remove from the oven and place the cupcakes immediately on a cooling rack. This prevents steam from building up underneath the cupcakes while cooling, causing the liners to separate.