1. Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking pan.
2. In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon, nutmeg, cloves, and salt.
3. In a large bowl, mix the pumpkin puree, granulated sugar, brown sugar, melted butter, vegetable oil, eggs, and vanilla extract until smooth and well combined.
4. Gradually add the dry ingredients to the wet mixture, stirring just until combined. If using, fold in the chopped pecans.
5. Pour the batter into the prepared baking pan and spread evenly.
6. To prepare the crumb topping, combine the flour, brown sugar, and cinnamon in a small bowl. Stir in the melted butter until the mixture resembles coarse crumbs.
7. Sprinkle the crumb topping evenly over the cake batter.
8. Bake for 35-40 minutes, or until a toothpick inserted in the center comes out clean. Allow the cake to cool in the pan on a wire rack.

Growing up, I learned the art of patience from my grandmother, who always insisted on letting baked goods cool properly before digging in. It’s a tough wait, but trust me, the flavors meld beautifully as the cake cools.