Preheat the oven and assemble the ingredients. Add granulated sugar and orange zest to a large mixing bowl and work the zest into the sugar with your fingers so that the fragrance is infused well.
Add the orange juice, orange oil, vegetable oil, buttermilk, and eggs to the bowl and mix to combine.
Now add the dry ingredients to the wet batter but be careful not to overmix.
Prepare the muffin tins and divide the batter into muffin liners.
Sprinkle coarse sugar over the tops of the unbaked muffins.
Bake the muffins for 20-25 minutes. Cool in the pan for a few minutes before transferring the baked orange muffins to a cooling rack.
Enjoy a delicious muffin as an afternoon snack or pair it with whipped cream.