Preheat oven to 375°F (190°C). Line a muffin tin with paper liners.
In a large bowl, whisk together flour, sugars, baking powder, baking soda, cinnamon, and salt.
In another bowl, mix milk, melted butter, eggs, and vanilla until smooth.
Combine wet and dry ingredients, stirring gently until just combined (do not overmix).
Divide batter evenly into muffin cups, filling about ⅔ full.
Make streusel: mix flour, brown sugar, and cinnamon, then cut in butter until crumbly. Sprinkle over muffins.
Bake for 18–22 minutes, or until a toothpick inserted in the center comes out clean.
Cool slightly; drizzle with glaze if desired.