Preheat oven to 350°F. Line muffin tins with paper liners or spray with cooking spray. Set aside.
Start by making the crumble topping.
With a fork, mix together sugars, flour, cinnamon, and salt.
Pour melted butter into dry mixture and use fork to mix together, allowing clumps to form. The larger the clumps, the larger the crumbs on top of the muffins will be. Set aside once mixed.
Mix dry ingredients together and set aside.
In a large bowl combine sugar, butter, eggs, and mix well.
Once incorporated, mix in sour cream/or yogurt and milk.
Then slowly add dry mixture to wet, mixing well. Use a whisk if needed to get out any clumps.
Mix in pumpkin until well incorporated.
Once mixed, use a large kitchen scoop or spoon to spoon batter into prepared muffin tins. Fill about ¾ full.
Sprinkle 1-2 tablespoons of crumb topping over each muffin. Bake in preheated oven for 20-25 minutes until tops spring back and/or until a toothpick inserted comes out clean.
Once slightly cooled, remove from tin and enjoy!