Make the Streusel: In a small bowl, whisk together the flour, brown sugar, cinnamon, and salt. Pour in the melted butter and stir with a fork until clumped and crumbly. Place the bowl in the refrigerator to chill while making the batter.

Prepare Oven & Pan: Preheat your oven to 350°F. Grease a standard 9×5-inch loaf pan and line it with parchment paper, leaving an overhang on the long sides for easy lifting later.

Whisk Wet Ingredients: In a large mixing bowl, whisk together the pumpkin purée, vegetable oil, brown sugar, and granulated sugar until smooth and completely combined. Whisk in the eggs one at a time until fully incorporated.

Add Leaveners & Spices: Sprinkle the baking powder, baking soda, salt, pumpkin pie spice, and cinnamon directly over the wet mixture. Whisk vigorously for 30 seconds to distribute the leaveners evenly throughout the liquid.

Fold in Flour: Add the all-purpose flour and gently fold with a rubber spatula just until the dry flour disappears. Do not overmix.

Top & Bake: Pour the batter into your lined 9×5 pan and smooth the top. Scatter the chilled streusel crumble evenly over the batter. Bake at 350°F for 65 to 75 minutes. A toothpick inserted into the center should come out clean or with a few moist crumbs.

Cool & Slice: Allow the bread to cool in the pan for 15 minutes. Use the parchment paper handles to transfer the loaf to a wire cooling rack. Cool completely before slicing.