Step 1

Grease or line two 8-inch round baking tins (I prefer spring-form pans for easy removal) and spray with cooking spray.

Step 2

Combine the ground flaxseed and water, then set it aside to thicken for a few minutes. Also, combine the milk and apple cider vinegar and set aside.

Step 3

Use a medium box grater (or grating disk on your food processor - this takes seconds!) to grate the zucchini - no need to peel first.

Step 4

Combine the cacao powder and melted coconut oil.

Step 5

Preheat the oven to 350ºF/180ºC.

Step 6

In a large mixing bowl, sift in all the dry ingredients and whisk the flour mixture to mix.

Step 7

Carefully pour in all the wet ingredients, including the shredded zucchini (no need to remove the excess liquid first).

Step 8

Stir the batter until well-incorporated, but make sure not to over-mix it. If using, now add chocolate chips/nuts.If it seems a little stiff, let it sit for a minute or two for the zucchini to release liquid and stir again.

Step 9

Divide the cake batter between the prepared pans, using a rubber spatula to help get all the batter from the bowl.

Step 10

Transfer the pans to the oven and bake for between 40-45 minutes, or until a toothpick inserted into the center of each cake comes out clean-ish (crumbs are fine, but no wet batter).

Step 11

Transfer the cakes to a wire cooling rack and leave them to cool completely. Then, carefully slice each cake in half to make four layers.

Step 12

To prepare the chocolate avocado frosting, blend all the ingredients together in a small blender or food processor. Start without the milk and then add to thin the frosting to your desired consistency. Taste and adjust any of the ingredients to your liking.

Step 13

With the cakes cooled, liberally spread the frosting between the layers, decorate the top (optional), slice, and enjoy!

Step 14

Make ahead: It's best to prepare the frosting fresh, but you can prepare the cake 1-2 days in advance, ready to frost before serving.Store: If you use the avocado frosting, the color and texture will be best on the day it's made. However, you can store the frosted cake in an airtight container in the fridge for 2-3 days.Freeze: It's best to freeze the cake unfrosted. Wrap it in two layers of plastic wrap, then transfer it to a freezer-safe bag for up to 3 months. Then thaw at room temperature, frost, and enjoy.