this is your basic recipe that you can add flavorings or ingredients to to make it your own
Homemade Cake Mix
7-1/2 cups sifted flour
1 tbs salt
4-1/2 cups sugar
4 tbs double acting baking powder
3/4 cup cold butter
In very large bowl, combine flour, salt, sugar and baking powder and mix well to blend. Cut the butter into small pieces and place in food processor bowl along with 2 cups of the flour mixture. Cover and process until mixture is very fine. Return to bowl with remaining flour mixture and mix well using a wire whisk.
Divide the cake mix into three equal portions (about 4 cups each) by lightly scooping the mix into measuring cups and leveling off with the back of a knife. Place each portion into a quart glass jar or heavy duty zip lock plastic bags. Cover tightly and store in the refrigerator for up to a month, or in the freezer for up to 3 months. Each portion of cake mix will make two 8" cakes or one 13x9" cake.
To bake:
4 cups Homemade Cake Mix
2 tsp your choice of flavorings (vanilla, lemon, orange, etc.)
1/4 cup butter, softened

3 eggs
1 cup milk
optional ingredients -- chocolate chips, nuts, chopped apple, etc.
Preheat oven to 350 degrees. Spray two 8" round cake pans OR one 13" x 9" cake pan with nonstick baking spray containing flour and set aside. Pour one portion of the cake mix into a large bowl. Make a well in center of mix and add flavoring, butter, eggs, and milk. Beat mixture 1 minute with electric mixer at low speed until blended. Scrape sides and bottom of bowl and beat 2 minutes longer at medium speed until batter is smooth. Blend in optional ingredients if using. Pour into prepared pans and bake the layer cakes at 350 degrees for 20-30 minutes, or until cake springs back when pressed lightly in center and begins to pull away from edges of pan. Bake the 9" x 13" cake for 25-35 minutes until the cake tests done. Use favorite icing.