Mix the cereal and buttermilk in a small bowl and let it rest for 10 minutes.
In a large bowl, beat the butter and the 1/2 cup of sugar together, then mix in the egg.
Add the cereal/buttermilk mix, the remaining dry ingredients, and half the orange zest, stir until mixed.
Take the other half of orange zest and mix it with 1/4 cup of sugar.
Line a muffin pan with cupcake liners. Spoon the batter into the cupcake liners, filling each between 1/2-3/4 full. Sprinkle each muffin with the zest/sugar mix.
Bake at 400° F for 15 minutes.