Prepare the avocado: Cut a ripe avocado in half, remove the pit, and scoop out the flesh. Mash until smooth or blend for extra creaminess. Measure out 1 cup.
Mix the dry ingredients: In a large bowl, whisk together cocoa powder, ground flaxseed, flour, baking soda, and salt. This keeps the cake soft yet structured.
Combine the wet ingredients: In another bowl, mix the mashed avocado, honey (or maple syrup), eggs, vanilla extract, and almond milk. Whisk until smooth and fully combined.
Make the batter: Gradually add the dry ingredients to the wet mixture, stirring gently. The thick, sticky batter creates a dense, fudgy cake—avoid overmixing.
Bake the cake: Preheat the oven to 350°F (175°C) and grease a 9-inch round cake pan. Pour in the batter, smooth the top, and bake for 25-30 minutes until a toothpick inserted in the center comes out clean.
Cool and serve: Let the cake cool in the pan for 10 minutes, then transfer to a wire rack. Enjoy as is or top with chocolate ganache or a dusting of cocoa powder.