There are two easy ways to replace fat with beans in most baking.
1. Simply cover beans with water and cook until very soft. Mash until about the consistency of shortening (use blender). Replace in recipes cup for cup. For example: Recipe calls for 1-cup margarine—use 1-cup mashed beans. Liquid may be added to adjust the consistency. Mashed beans do not keep long in the fridge, so freeze them.
2. Grind beans in your wheat grinder to make bean flour. Store in an airtight container. Replace fat in the recipe cup for cup as above. You will need to add extra liquid since the ground beans will be part of the dry ingredients.
Other types of beans will work, including canned beans. The type of bean will have an effect on the taste. White beans give it a slight vanilla taste. Some people say that the color of the bean should match the color of what you are baking.