• Prep: Preheat the oven to 350℉. Line the pan with parchment paper and set aside. Lightly wash the blueberries and lightly pat them dry, don't dry them completely.
  1 1/2 cups fresh blueberries

For the streusel

• In a medium sized bowl, add flour, sugar, and softened butter. Using your hands, mix until crumbly and combined. Set aside while you make the muffin batter.
  3/4 cup all-purpose flour, 5 tbsp butter, 1/3 cup white sugar

For the cake

• In a medium sized bowl, add in the dry ingredients. Stir to combine and set aside.
  2 cups all-purpose flour, 1 tsp baking soda, 1 tsp baking powder, 1/4 tsp salt, 1 tbsp cornstarch
• In a large bowl, add lemon zest and white sugar. Using your hands, rub the two ingredients together for about a minute. This helps release the lemon zest aroma and flavours.
  1 tbsp lemon zest, 3/4 cups white sugar
• Into the same bowl, add in the oil, eggs, vanilla, and buttermilk. Continue mixing for another 2-3 minutes until smooth.
  1/2 cup oil, 2/3 cups buttermilk*, 1 tbsp vanilla, 2 eggs
• Add the dry ingredients in and with a spatula, mix until a batter forms. Do not over-mix!
• Gently toss the blueberries in 1-2 tsps of flour before adding them into the mixing bowl. This will help them not sink as it bakes. Then add into the bowl and mix in a few times.
  1 1/2 cups fresh blueberries
• Spread the batter into the prepared pan evenly and sprinkle the streusel evenly on top.
• Bake for 40-50 minutes. It really depends on your oven, but after 35 minutes I would start checking with a toothpick to see if it's ready! A toothpick should come out clean.
• Allow to cool, slice, and enjoy!