Preheat oven to 375°F (190°C). Line muffin tin with paper liners.
In a large bowl, whisk flour, sugar, baking powder, baking soda, and salt.
In another bowl, combine melted butter, eggs, sour cream, milk, and vanilla.
Fold wet mixture into dry until just combined (do not overmix).
Gently fold in blueberries.
Divide batter evenly into prepared muffin tin.
For streusel: mix flour, brown sugar, cinnamon, and melted butter until crumbly. Sprinkle evenly over muffins.
Bake for 20–25 minutes, until golden brown and a toothpick comes out clean.
Cool on a wire rack.
For glaze: whisk powdered sugar, lemon juice, and zest. Drizzle over cooled muffins before serving.