To Make the Muffins:

1. Preheat oven to a true 350°F (using an oven thermometer ensures that you get to the right temperature!).  Prepare a 12-cup muffin pan with muffin liners and set aside.  
2. Sift the 320 g flour, 1 tsp salt, and 1/2 tsp baking soda into a medium-sized bowl.  Set aside.
3. Place the butter and oil into a large mixing bowl or the bowl of your stand mixer.  Mix until the butter and oil is completely smooth.  Add the sugar and cream the mixture until light and fluffy.  (Need help figuring out what it means to “cream butter and sugar until light and fluffy”?  Check out this post!)
4. Add eggs, one at a time, mixing until each egg is completely incorporated.  Scrape the sides and bottom of the bowl as needed to ensure even mixing.
5. Add the pure vanilla and Creme de Cassis (if using) and mix until completely combined. 
6. Add half of the flour mixture and mix until nearly combined.  Scrape the sides and bottom of the bowl to make sure that there is no flour at the bottom.
7. Add all of the buttermilk and mix until nearly combined.
8. Add the second half of the flour mixture and mix until nearly combined.  
9. Finish mixing with a rubber spatula, mixing only until no streaks of flour remain.
10. Place the blueberries and the remaining two tablespoons of flour into a small bowl.  Stir thoroughly to coat.
11. Use a sifter or fine mesh strainer to remove excess flour from the blueberries.  We don’t want extra flour in this batter!
12. Gently fold the blueberries into the batter.  Using an ice cream scoop or a 1/3 cup measuring cup, place batter into the prepared muffin cups.  Top each muffin generously with the turbinado sugar.
13. Bake at 350°F for 25-30 minutes, or until a toothpick comes out clean.  Allow to cool in the muffin pan for three minutes, then remove to a wire cooling rack to cool completely.
14. Enjoy!