• Preheat Oven to 425F. Line pan with muffin liners or paper liners.
• In a large bowl add all the wet ingredients (Melted Butter, Oil, Sugar, Eggs, Vanilla Extract, Buttermilk and Sour Cream.)
• Add the dry ingredients to the wet ingredients and mix until almost combined.
• Add blueberries into the muffin batter and fold until just mixed in. (Make sure to read tips about using fresh or frozen blueberries)
• Divide and scoop the blueberry muffin batter into each tin filling almost to the tops of the pan.

Crumb Topping:

• In a medium sized bowl add in flour, brown sugar, sugar and salt. Add the melted butter over the dry ingredients and mix together with a fork until it comes together.
• Top generously with turbinado sugar or crumb topping on the top of each muffin.

Bake:

• Bake the muffins for 20 to 25 minutes or until a toothpick is inserted clean.
• Allow the blueberry muffins to cool on the rack for 5 to 10 minutes and then allow them to cool on a wire rack.
• Store leftover blueberry muffins in an airtight container.