Preheat oven to 425 F.
Line muffins pan with liners or spray with cooking spray and set aside.
In a large bowl or stand mixer fitted with a paddle attachment, cream together butter, oil, and sugars.
Add in eggs one at a time, beating between each addition.
Add in vanilla extract.
Stir together flour, baking soda, baking powder, nutmeg and salt in a medium bowl and add to the wet ingredients alternating with the buttermilk. Mix until fully combined.
Gently fold in blueberries with a rubber spatula.
Add a 1/4 cup of batter to each of the muffin cups and sprinkle with coarse sugar.
Bake for 15 - 18 minutes.
Remove the muffins from the pan and place on a cooling rack.