In a large bowl, combine the bran cereals and the boiling water. Let stand and soften.
Get out an extra large lidded bowl ( the largest Tupperware is the most common one used). Using a hand mixer or a wooden spoon, cream the butter and sugars together until blended completely.
Add in the eggs and beat well, until the mixture is light and creamy.
Stir in the buttermilk and molasses, and mix until combined.
Add in the softened cereal mixture and stir to combine.
In another bowl, whisk together the flour, baking soda, baking powder, salt and raisins.
Add the dry mixture to the batter in the large Tupperware bowl.
Stir until JUST combined.
Cover tightly and store in the refrigerator.
It will keep for up to six weeks.
To Bake Fresh
Preheat your oven to 400 °F. Lightly grease muffins tins, or use paper liners.
Stir the batter and fill the muffin cups 2/3 full with batter.
Bake in the oven for 15-20 minutes, until the muffin tops spring back when lightly touched and a toothpick inserted into the middle comes out clean.
Remove and place on cooking racks to cool.
Notes
A half batch of this will make 12 of the oversized or bakery sized muffins. they will need 5-10 extra minutes baking at 375° if you do oversized muffins.