Preheat oven to 350° F and line a 12-cup muffin tin with paper liners or coat with non-stick cooking spray.
Begin making the crumb topping by combining sugars, cinnamon and salt in a bowl. Stir in the melted butter. Stir in the flour until all the ingredients are combined and creates crumbly texture.
In a separate bowl, combine flour, sugar, baking powder, cinnamon, baking soda, and salt. Add milk, oil and egg and stir until just combined.
Pour or scoop batter evenly between the 12 muffin cups. Sprinkle crumb topping over the batter using your fingers to gently press down into muffin batter.
Bake at 350° F for 15-18 minutes or until toothpick inserted in center comes out clean.
For optional glaze, mix powdered sugar and milk in small measuring cup until combined and smooth. For thicker glaze, add more powdered sugar and thinner glaze, add more milk.
Let cool completely and drizzle with glaze before serving.