Step 1

Position an oven rack in the middle of the oven. Preheat oven to 350F degrees. Spray a 9-inch round cake pan with cooking spray.

Step 2

To make the streusel topping, in a small bowl combine the flour, brown sugar, 1/2 teaspoon cinnamon, butter and canola oil with a fork or your fingers until the mixture is crumbly. (Add about a teaspoon of apple juice or milk if you need a little more moisture to achieve a crumbly consistency.) Stir in the Grapenuts and set aside.

Step 3

To make the cake, in a small bowl, whisk together the flour, baking powder, pumpkin pie spice, baking soda and salt until well combined.

Step 4

In a large mixing bowl, Whisk together the eggs, pumpkin, buttermilk, brown sugar, sugar, canola oil and vanilla until well blended. Add the flour mixture and stir just until combined.

Step 5

Scrape the batter into the prepared pan. Sprinkle the streusel topping evenly over the top of the cake.

Step 6

Bake in the preheated oven until a wooden toothpick inserted in the center comes out clean, 45 to 50 minutes.

Step 7

Remove from the oven and place on a wire rack to cool for 15 minutes. Serve warm.