Step 1

Preheat the oven to 325F. Spray a round 8-inch cake pan (with at least 2-inch sides) with baking spray. Line the bottom of the pan with a circle of parchment paper. (If your pan does not have 2 inch sides, use a 9-inch round pan.)

Step 2

In a medium-size, microwave-safe bowl, melt the butter in the microwave for 1 minute on high power. Add the walnuts (if using) brown sugar, flour, baking powder, cinnamon and salt. Stir with a fork until well-combined and crumbs start forming. Set aside until ready to use. The crumbs will firm up as they sit.

Step 3

Whisk together the sugar, oil and eggs until smooth. Add the zucchini, pineapple and vanilla and stir until well combined.

Step 4

Sprinkle the baking soda, baking powder, salt and cinnamon over the top and stir to combine. Add the flour and stir just until all of the flour is incorporated.

Step 5

Transfer the batter to the prepared pan and bake for 20 minutes. Carefully remove the pan from the oven and gently top with the crumb topping.

Step 6

Return the pan to the oven and bake for another 18-25 minutes(a total time of 38-45 minutes), until the center is firm when touched lightly on the top of the cake. You can also test the doneness with a toothpick inserted into the center of the cake. It will come out clean or with just a few crumbs when the cake is done. You can also test the doneness with an instant thermometer which should register 205-210˚F when the cake is finished.

Step 7

Allow the cake to cool for 10 minutes then invert onto a clean plate. Invert again onto a cooling rack so that the crumb topping is back on the top. Allow the cake to cool for 15-20 minutes before adding the drizzle.

Step 8

Combine powdered sugar, milk (or half and half) and vanilla and stir well with a small whisk or a fork. Drizzle over the top of the cake and ENJOY!