Heaven Cakes!

I think you replace 1/2 cup of the oil with a 1/2 cup of applesauce. Sp if your recipe calls for 3/4 cup oil 1/2 cup applesauce, 1/4 cup oil.If I come across any further tips I’ll come back to edit.
References :

6 tbsp. butter
1 c. brown sugar
1 egg
1/2 c. applesauce
1 tsp. shredded orange peel
1 tsp. vanilla
1 1/2 c. sifted flour
1 tsp. baking powder
1/2 tsp. salt
1/4 tsp. soda
1/2 c. nuts

Mix butter, brown sugar, stir in egg, applesauce, vanilla, orange peel, add flour, baking powder, salt, soda. Bake at 350 degrees for 35 minutes. When brownies are still warm from oven, pour on topping on follows: 1/2 tsp. vanilla Dash of salt Approximately 2 tbsp. orange juice
References :
http://www.cooks.com

This site says to use 2/3 of whatever oil is used. I would go with a little less if what you’re baking is on the lighter side, and a little more if it’s heavier
References :
http://www.recipetips.com

(Low Fat Recipe Substitutions)

1-1/2 cups white sugar
1/2 cup margarine
2 eggs
2 Tbs. unsweetened cocoa powder
1-1/2 tsp. salt
2 cups applesauce
1 tsp. baking soda
1 tsp. ground cinnamon
2 cups all-purpose flour
2 Tbs. white sugar
1 cup semisweet chocolate chips
1 cup chopped walnuts (optional)

Preheat oven to 350 degrees. Cream sugar and margarine, add eggs. Sift cocoa, salt, baking soda, cinnamon and flour together and add to sugar mixture alternately with applesauce. Pour into 10-1/2 x 15-1/2 inch jelly roll pan. Combine 2 Tbs. sugar, chocolate chips and nuts (if desired) and sprinkle over batter. Bake for 30 minutes.
References :

I don’t know about applesauce, but add choc. chips and walnuts…YUM!!
References :