Many Muffins Mix
10 cups whole wheat flour (I use freshly ground, but that is not necessary.)
5 cups oat flour (I chop the whole oats fine in my blender instead.)
5 cups all-purpose flour (I usually use more whole wheat flour here instead unless I've purchased my wheat flour rather then grinding it. For some reason the store bought wheat flour flour will make a crumbly and drier muffin making the white flour necessary.)
4 cups sugar (For a less sweet muffin -- Use 2 1/2 cups instead.)
2 1/2 cups dry milk
3/4 cup baking powder
1 1/2 T. salt
2 T. cinnamon (optional)
1 t. nutmeg (optional)
Measure all ingredients into a large bowl. Mix ingredients well. The mix may be stored in an air tight container or you may divide it into 2 1/2 cup portions in freezer bags or small containers to freeze until ready to use. Our large family uses the mix quickly enough that I just store it on my counter. A batch of mix will last us about a month. However, freshly ground wheat flour can spoil quickly in warm humid weather, so make sure to refrigerate or freeze it if it will not be used rapidly.
To prepare the muffins measure out 2 1/2 cups of mix into mixing bowl. Add ingredients for Basic Muffins unless they are adjusted in the variation you choose. Then add ingredients to make whichever variation of muffin you desire. Pour batter into greased muffin tins. Use approximately 1/3 cup of batter for each muffin. Bake at 325 for 17-22 minutes. Makes 1 dozen muffins.
The rest of the information is at the above link.