Preheat oven to 450°F. Lightly spray a muffin pan with nonstick spray or line with paper cups.
In a medium sized mixing bowl soak bran cereal and buttermilk for about 10 minutes until it gets all soggy.
Add in melted coconut oil, egg, brown sugar, vanilla extract, flour, baking soda, baking powder and salt. Stir thoroughly. This mixture will be very thick.
Divide the batter equally among the 12 muffin cups, filling almost all the way full.
Bake in the preheated 450°F oven for 5 minutes. Without opening the door, reduce the heat to 350° and let the muffins continue baking another 8 to 10 minutes. Remove from the pan and cool on a wire rack.