Best Homemade Blueberry Muffins

Preheat the oven to 425 degrees F and prepare a muffin pan with paper liners; set aside
In a large bowl, combine the flour, granulated sugar, baking powder and salt; set aside
In a medium bowl, whisk together the eggs, buttermilk, vegetable oil, melted butter, lemon zest and vanilla extract
Combine the wet ingredients into the dry ingredients and gently whisk until fully combined and batter is smooth (don't over mix)
Using a spatula, fold the fresh blueberries into the muffin batter
Fill the muffin liners with ¼ cup of batter into each
Make the Crumbling Topping: combine all the ingredients in a small bowl and mix until fully combine and turns into a crumble
Evenly divide the Crumble Topping and sprinkle it on top of each muffin
Bake the muffins in the preheated oven for 14-15 minutes
Remove the muffins from the oven and allow them to cool
Eat warm or at room temperature and store then remaining muffins in an air tight container for 2-3 days