For the Crumb Topping: In a medium bowl, mix together the flour, pecans, brown sugar, and salt. Pour in the melted butter and stir just until everything is combined. Set the mixture aside while you prepare the rest of the recipe. As it sits, the butter will be absorbed, making the topping more crumbly and ready to use.

For the Filling: In another medium bowl, combine the brown sugar, cinnamon, and cocoa powder until evenly mixed. Set this aside until you’re ready to use it.

For the Cake: Preheat the oven to 350°F. Line an 8- or 9-inch square metal baking pan with parchment paper, leaving two sides with overlapping edges for easy removal. Spray the parchment paper and any exposed areas of the pan with nonstick baking spray. Set aside. (Note: if using a glass or ceramic pan, you may need to increase the baking time.) In a large bowl, whisk together the oil, sour cream, molasses, eggs, vanilla extract, brown sugar, pumpkin puree, spices, salt, baking powder, and baking soda until the mixture is smooth. Using a rubber spatula, gently fold in the flour until just combined and smooth. Avoid overmixing. Spread half of the batter evenly into the prepared pan, pressing it out to the edges. Sprinkle the filling evenly over the batter layer. Carefully spread the remaining batter over the filling, smoothing it out. Then evenly sprinkle the crumb topping over the entire surface. Bake for 55 to 60 minutes, or until the crumbs turn golden brown and appear dry, and a toothpick inserted in the center comes out clean. Remove the cake from the oven and transfer it to a wire rack to cool completely before lifting it from the pan, slicing into squares, and serving—perfect alongside a cup of coffee!

For the Glaze: In a medium bowl, whisk together the confectioners’ sugar, maple syrup, milk, and vanilla extract. If the glaze is too thick to drizzle, add an additional teaspoon of milk, a little at a time, until the desired consistency is reached. Drizzle the glaze over the cooled cake and let it set for about 5 minutes before serving.