Preheat oven to 350° F. Line a muffin tin with muffin liners.
In a large mixing bowl, combine granulated sugar, light brown sugar, vegetable oil, eggs, milk, vanilla extract and pumpkin puree. Whisk until combined and smooth.
Add in all-purpose flour, baking soda, salt, and cinnamon. Whisk until well combined and smooth, but do not overmix the batter.
Portion the batter into muffin liners using a large cookie scoop to approximately ⅔ full. Set aside.
In a small bowl, combine melted butter, brown sugar, all-purpose flour, and cinnamon. Mix to combine until crumbly.
Sprinkle the streusel topping over the muffin batter. Divide evenly over the muffins.
Bake the muffins for 22-24 minutes until an inserted toothpick comes out clean.
Cool in the pan for about 5 minutes. Transfer to a wire rack to cool completely.
In a small bowl, combine powdered sugar and milk. Mix until smooth.
Use a spoon to drizzle the glaze over the cooled muffins.