Best Blueberry Muffins with Crunchy Streusel Topping - My Homemade Recipe

Ingredients

• 1/2 cup all-purpose flour (72g)
• 1/2 cup sugar (112g)
• 1/2 teaspoon ground cinnamon
• 1/4 cup butter, melted (salted or unsalted)
• 1.5 cups all-purpose flour (212g)
• 3/4 cup granulated sugar
• 2 teaspoons baking powder
• 1/4 teaspoon kosher salt
• Zest of 2 meyer lemons (or 1 orange plus 1 lemon)
• 1/3 cup unsalted butter, melted (5.33 tablespoons)
• 1 large egg
• 2/3 cup buttermilk
• 2 cups blueberries (fresh or frozen)