In a large bowl add the bran flakes.: As the bran hits the bowl you will notice the dry, brittle texture and toasted aroma, which foreshadows the nutty note it will introduce once hydrated. Use a large glass or metal bowl so the hot water does not warp anything, and make sure there is room to stir comfortably. A common mistake here is using a bowl that is too small which leads to spills when you add boiling water.
Pour the boiling water over the top, and mix well. Stir every couple of minutes while the mixture cools to room temperature. The mixture will be thick and sticky.: Immediately the bran soaks and swells, releasing steam and a warm, toasted scent. Stirring every couple of minutes while it cools ensures even hydration and prevents clumps, giving a uniformly thick, sticky mixture that folds into the batter. If you leave the bran unturned it can clump into dense pockets that break the muffin texture.
In a large bowl with a tight fitting lid (needed if you aren't baking the muffin batter right away), cream together shortening and sugar. Mix in eggs, salt baking soda until combined.: Creaming produces a pale, slightly fluffy mass that traps air, and you will hear a soft scraping sound as the paddle moves through softened shortening. This step is crucial because it distributes fat evenly, which yields tender muffins. A common oversight is rushing this phase, which results in pockets of unincorporated shortening and uneven crumb.
Mix in flour and buttermilk, alternating ingredients as you add them and mixing. Add in the All-Bran Cereal and cooled bran flakes mixture and stir until combined.: When you add each egg, the batter will glossy slightly and gain elasticity, and the scent becomes richer. Mixing until just combined avoids overworking the batter, which would make muffins tough. Watch for a smooth, cohesive texture; if you over mix, the muffin tops may be flat and tight.
Spoon batter into muffin cups coated with non-stick spray or with muffin cup liners. They should be 2/3 full. Bake at 350 degrees for 20 minutes.: Alternating keeps the batter balanced and prevents lumps, and you will notice the batter shift between thick and more fluid states. This technique yields a tender crumb by preventing over development of gluten. A frequent error is dumping all flour at once, creating pockets of dry flour or a gummy batter from overmixing.
Add in the All-Bran Cereal and cooled bran flakes mixture and stir until combined: The batter will thicken noticeably and take on flecks of bran, giving a hearty appearance and a slightly grainy mouthfeel that I love. Stir until the mix is uniform, but do not beat; over stirring will make muffins dense. If the cereal remains dry on the edges you probably did not hydrate the bran enough, which will create dry pockets in the muffins.
Spoon batter into muffin cups coated with non-stick spray or with muffin cup liners: As you fill each cup watch the batter settle and smooth slightly on top, showing you the right consistency. They should be two thirds full so the tops can rise without overflowing. A common mistake is overfilling which leads to merged domes and uneven baking.
They should be 2/3 full: Keeping that consistent fill level gives even rise across the tray, producing uniform muffins that brown at the same rate. I use a small ice cream scoop for quick, repeatable portions to avoid mismatched sizes. If one pan has much more batter than another, the bake time will vary and some muffins may be underdone.
Bake at 350 degrees for 20 minutes: During baking the kitchen will fill with a toasty, wheaty aroma and the tops should turn a warm golden brown. You can test doneness with a toothpick which should come out clean or with a few moist crumbs, and the sides will slightly pull away from the pan. Opening the oven early or setting temperature too high causes rapid doming and potential overbrowning, so keep the oven steady for even results.