In a small mixing bowl combine the sugars, flour, and butter. Mix until tiny crumbs have formed, the mixture should be uniform, set aside.
For the muffins:
Preheat oven to 375 degrees F, grease or line a 12 cup muffin tin, set aside.
In a large mixing bowl combine the oil, sugars, eggs, milk, and vanilla extract. Whisk until combined. Add in the pumpkin puree, mix again.
In a small mixing bowl combine the flour, baking powder, baking soda, cinnamon, and salt, stir to combine.
Add the dry ingredients into the wet and combine until completely incorporated.
Use a portion scoop to fill each muffin cup 2/3rds full. Top each muffin evenly with the streusel mixture, gently press into the batter.
Bake at 375 for 25-30 minutes, until a toothpick inserted into the middle comes out clean. Transfer to a cooling rack and allow to cool before enjoying!