First make the streusel topping. Combine the flour, sugar, butter, cinnamon, and pecans in a bowl until crumbly.
Then whisk together the sugar, brown sugar, oil, and melted butter in a mixing bowl.
Whisk in the eggs, pumpkin, and vanilla extract until combined.
Then fold in the flour, cinnamon, baking powder, baking soda, and salt until just combined.
Pour the pumpkin batter into a loaf pan lined with parchment. Top with the streusel. Bake at 350 for 50 minutes.