Making the streusel for the pumpkin muffins:Combine the flour, sugars, cinnamon, and salt in a medium sized bowl.
Pour in the melted butter and mix until it has been absorbed by the flour and large crumbs have formed. Set aside.
Instructions for making the muffins:Preheat your oven to 375°.
Line two 12 cup muffin pans with paper muffin liners, or spray the cavities with cooking spray.
Melt butter in a small saucepan or the microwave. Once melted, set aside to cool slightly while you prepare the other ingredients.
Whisk together flour, baking soda, spices, and salt in a medium sized bowl and set aside.
Next, whisk the sugars, melted butter, and vegetable oil together until combined. It'll start to separate immediately, but that's ok!
Mix in the eggs and vanilla extract. Continue mixing until well incorporated.
Add the pumpkin to the egg mixture and whisk until all the wet ingredients are blended together.
Pour the pumpkin mixture into the dry ingredients and using a whisk or a wooden spoon, mix until the batter is just combined and no flour streaks remain. Do not over mix!
Scoop muffin batter (about a 1/4 cup) into paper muffin liners.
Top all the muffins with the streusel crumb mixture.
Bake muffins at 375° for about 17-20 min.
The muffins are done when an inserted toothpick comes out clean.