• Preheat the oven to 425℉/218℃. Line a muffin tin with liners and set aside. Grate the orange zest and juice the oranges (if using fresh orange juice).
  1 tbsp orange zest, 1/4 cup orange juice

For the streusel

• Combine white sugar, flour, and softened butter in a bowl with your hands or a fork until a crumbly streusel forms. Place in fridge to chill while the muffin batter is made.
  3/4 cups all-purpose flour, 1/4 cup white sugar, 5 tbsp unsalted butter

For the muffins

• Add the flour (2 1/2 cups, leave the 1 tsp to dust the blueberries in later), baking soda, baking powder, cornstarch, and salt into a bowl. Mix together and set aside.
  2 1/2 cups all-purpose flour, 1 tsp baking soda, 3 tsp baking powder, 2 tsp cornstarch, 1/4 tsp salt
• In a large bowl, add the orange zest and white sugar. With your fingers, rub together for about a minute and combine.
  1 cup white sugar, 1 tbsp orange zest
• Into the same bowl, add in butter, oil, eggs, vanilla, buttermilk, and orange juice. Whisk well to combine.
  1/2 cup unsalted butter, 4 tbsp oil, 2 large eggs, 1 tbsp vanilla, 3/4 cups buttermilk*, 1/4 cup orange juice
• Add the dry and wet ingredients together just until a soft muffin batter forms. Do not over-mix!
• In the bowl with the blueberries, add 1 tsp of flour and gently coat the berries. Then add them into the batter and mix in a few times. Don't over-mix!
  1 1/2 cups fresh blueberries
• Scoop the muffin batter into the liners (I like to use a cookie scooper for this as it's quicker and less messy). Fill them to the top. Then sprinkle a handful of streusel on top of each muffin.
• Bake for 5 minutes at 425℉/218℃, then lower to 375℉/190℃ and continue baking for 15-20 minutes or until a toothpick inserted in the middle comes out clean. Allow to cool, and enjoy!
• These muffins are so delicious!