In a mixing bowl combine the flour, granulated sugar, baking powder, salt, and nutmeg or cinnamon. Stir with a spoon to combine and set aside.
In a larger mixing bowl combine the eggs, buttermilk, vegetable oil, melted & cooled butter and vanilla extract. Stir to combine with a spatula.
Gradually mix in the dry ingredients, mixing just until combined. Using a spatula, gently fold in your desired add-ins. The batter will be very thick!
Cover the bowl with a towel and allow the batter to rest for 15 minutes. During this time, preheat the oven to 425ºF.
For bakery style muffin tops, line a 12 count muffin pan with 6 muffins liners, meaning you’ll only fill every other muffin well with batter. Fill the liners to the top with batter. Use a butter knife to smooth the tops of the muffins if lumpy. Press additional add-ins on top of the muffins and sprinkle with sanding sugar.
Bake for 7 minutes at 425ºF, then keep the muffins in the oven, and turn the temperature down to 350ºF and bake for 15-20 minutes or until a toothpick inserted in the center comes out clean. Allow the muffins to cool in the pan before removing.
