In a large mixing bowl, pour boiling water over two cups of bran cereal, and let it sit until water is absorbed. Stir in shortening or vegetable oil.

NOTE if using shortening: although melted when added to the bran cereal, shortening will begin to harden when combined with the buttermilk/egg mixture. To prevent this, bring the buttermilk and eggs to room temperature prior to using them.

In a second bowl, combine remaining bran cereal, sugar, eggs and buttermilk. Set aside.

Sift together flour, baking soda and salt. Combine all mixtures. If desired, add rasins or dates.

Fill greased or paper-lined muffin tins with batter and bake in 400°F oven for 16 to 20 minutes.  Test doneness by inserting toothpick. If it is batter-free when withdrawn from the muffin, the muffins are done. Cool on wire rack.

Store unused batter in airtight container in refrigerator for up to 6 weeks. When baking refrigerated batter, add about 2 minutes to cook time.