Preheat oven to 350 degrees.
Grease a muffin tin or line with cupcake liners.
Combine flour, baking soda, baking powder, salt, sugar, and cinnamon in a large bowl.
Mix pumpkin puree, sour cream, milk, oil, vanilla, and eggs in a separate large bowl.
Add dry ingredients to wet ingredients and mix until just combined.
Spoon batter into muffin tin, adding equal amounts to each muffin well.
For sugar topping, combine sugar and brown sugar in a small bowl.
Sprinkle brown sugar mixture evenly over muffin batter.
Bake in a 350 degree oven for 18-23 minutes.