I've baked a lot of bran muffins in my day. This by far takes the cake. I was skeptical at first about the Bran Flakes and buttermilk, but the end product was deleted any and all doubts.
When I made them, I divided the recipe in half (seeing that it made for it made quite a few servings). From there, I substituted margarine for shortening (surprisingly made no difference in texture or volume, only intensified the taste), used whole wheat pastry flour instead (again, no difference, just a boost in nutrition), swapped a 1/3 cup of sugar for 2 tbs. of honey, and FINALLY coated the top of the muffins with brown sugar before baking. This made for a delicious and presentable muffin that is more pleasing to the eye than just a regular old bran muffin.
So I made a few personal alterations.. nothing major. I'm sure the basic, original recipe would bake out the same results. All in the all, the muffins were amazingly tasty and had even the pickiest eaters coming back for seconds..and thirds.
PS: I refrigerated them overnight.