Preheat the oven to 375.
Line muffin tins with paper cupcake liners OR lightly spray with cooking spray.
Combine all dry ingredients in a largish mixing bowl and whisk them together. If your flour, baking powder or baking soda are lumpy, be sure to fun them through a sieve to remove the lumps before proceeding.
Mix the buttermilk and oil in a 2 cup glass measuring cup. Then add the egg and, using a wire whisk or fork, beat all the wet ingredients together until thoroughly mixed.
Add the buttermilk mixture to the flour mixture, and gently fold them together using a rubber spatula. It’s important that you don’t over mix the batter, as this will result in excess gluten development and tough, chewy muffins.
Gently fold the blueberries into the batter until evenly distributed.
Scoop batter into muffin tins. For best looking muffins I use my faithful food scoop. Sprinkle generously with coarse sparkling sugar. Bake for 20-24 minutes until a toothpick comes out clean. No toothpick? Press lightly on the muffin top — it should feel firm but not hard. Also, the muffin edges should be just lightly brown. In my oven the muffins take 22 minutes.
Let cool in the pan for about 10 minutes, then loosen muffins with a knife. Remove to a wire cooling rack or prop at an angle in the muffin tin so bottoms don’t get soggy.