• Preheat the oven to 375°F/190℃. This recipe makes 15 regular-sized muffins and 8 tulip liner muffins. Line the muffin tins with your liners and set aside.

For the streusel

• In a small bowl, make the streusel. Combine flour, white sugar, and cold cut up butter. Using your hands, mix it together until combined into a crumbly, streusel mixture. Set aside while you make the muffin batter.
  3/4 cup all-purpose flour, 5 tbsp butter cold, 1/3 cup white sugar

For the muffins

• In a medium-sized bowl, add in flour, rolled oats, baking soda, baking powder, cornstarch, and salt. Mix together and set aside.
  1 1/2 cups all-purpose flour, 1 cup rolled oats, 1 tsp baking soda, 1 1/2 tsp baking powder, 1 tbsp cornstarch, 1/4 tsp salt
• In a large bowl, add white sugar and lemon zest. Using your fingers, combine them to release all of the lemon oils and fragrances. Do this for 2 minutes.
  3/4 cups white sugar, 1 lemon
• Into the same bowl, add oil, eggs, vanilla, and buttermilk. Whisk until well combined.
  1 tbsp vanilla, 1/2 cup oil, 1 cup buttermilk*, 2 eggs
• Add in dry ingredients. Pour the dry ingredients into the wet and using a spatula, gently fold to create a soft muffin batter.
• Gently toss the blueberries in 1-2 tsps of flour before adding them into the mixing bowl. This will help absorb any liquid they may have from washing and prevent from sinking. Then add into the bowl and mix in a few times.
  1 1/4 cup fresh blueberries*
• Evenly divide the batter between your liners, they should be almost full. Using a cookie scooper helps big time to minimize the mess. Sprinkle a handful of streusel on top.
• Bake the muffins at 375°F for 20-25 minutes. If using regular liners, the muffins will bake for 15-20 minutes. The muffins are ready when a toothpick inserted comes out dry with no wet batter.
• These muffins stay fresh covered at room temperature for a few days, or in the refrigerator in an airtight container for up to 1 week!