I don’t usually substitute ingredients when I bake, but here are five substitutions that I use all the time.
Buttermilk — To make one cup of buttermilk, combine 1 tablespoon of vinegar or lemon juice with enough milk to fill a one cup measure. Stir well. Let stand for at least five minutes before using.
Self-Rising Flour — Add 1/2 teaspoon salt and 1 1/2 teaspoons baking powder to one cup of all-purpose flour for each cup of self-rising flour called for in the recipe.
Brown Sugar — Mix 2 tablespoons of molasses into one cup of granulated sugar to replace one cup of brown sugar.
Unsweetened Chocolate — Use 3 tablespoons cocoa and one tablespoon oil instead of one square of unsweetened chocolate.
Baking Powder — Combine 1/4 teaspoon baking soda and 1/2 teaspoon cream of tartar to replace one teaspoon of baking powder.

Marguerite daisy (Argyranthemum frutescens)
Racquel
One Egg = 2 tsp flax meal whipped til gooey with 3 tsp water
Pamela
I tried the cake in the pan and it was and easy to do. I was low on vegetable oil and added melted margarine.
I’d like to replace the cocoa powder with lemon juice for a twist on the actual recipe and possibly a 1/2 cup os sugar.
Well, I’ll find out soon enuf — I enjoy testing recipes and adulterating some of the items.