Adjust the oven rack to the 2nd level position (just above center) and preheat the oven to 425ºF. Line a standard size cupcake or muffin tin with tulip style or standard size liners.
In a medium-size bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt. Set aside.
In a separate large-size mixing bowl, whisk together the eggs, cooled melted butter, vegetable oil, granulated sugar, buttermilk, and vanilla extract, mixing until fully incorporated.
Add in the dry ingredients along with the semi-sweet chocolate chips to the wet mixture and mix until just combined.
Using a 2-3 tablespoon-size cookie scoop or 2 spoons, divide the batter evenly into the 12 muffin liners. Top with a sprinkling of sparkling sugar and a few more semi-sweet chocolate chips (optional).
Bake for 8 minutes at 425ºF, then reduce the temperature to 350ºF (keep the oven door closed) and bake for an additional 12-15 minutes or until an inserted toothpick comes out clean. The tops should also be light golden brown in color.
Remove from the oven and allow to cool for 5 minutes before removing muffins from the tin. Chocolate chip muffins are best served slightly warm, but enjoying them completely cooled is just as good!