Make the Streusel by combining all-purpose flour, brown sugar, cinnamon, and a pinch of salt. Add melted butter and mix until resembling coarse crumbs. Refrigerate to firm up.

Preheat your oven to 350°F (175°C) and prepare a loaf pan by greasing with butter or non-stick spray and lining the bottom with parchment paper.

In a large bowl, whisk together pumpkin puree, vegetable oil, brown sugar, and granulated sugar until smooth and well combined.

Incorporate the eggs one at a time, mixing well after each addition until the mixture is thick and creamy.

Mix in the baking powder, baking soda, salt, and cinnamon over the wet mixture and whisk until fully incorporated, avoiding overmixing.

Fold in the all-purpose flour gently until just combined, maintaining small lumps.

Pour the batter into the prepared pan, smooth the top, and distribute the streusel topping evenly over the batter.

Bake for 65-80 minutes, checking for doneness with a toothpick inserted into the center.

Let cool for 10-15 minutes, then transfer to a wire rack to cool completely before slicing.