Preheat oven to 350°F. Line a 9‑inch cake pan with parchment paper.
In a large bowl whisk together the eggs, sweet potato, olive oil, maple syrup and vanilla until smooth. Sift in the flour, cacao powder, baking soda, salt, and espresso powder; mix until the batter is uniform.
Pour the batter into the prepared pan and bake for 25‑30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Cool in the pan 10 minutes then transfer to a wire rack to cool completely.
While the cake cools, make the frosting: blend the avocados, maple syrup and cacao powder in a food processor until silky and fluffy.
Once the cake is completely cool, spread the frosting evenly over the top. Slice, serve, and enjoy!
Notes
For extra chocolate intensity, drizzle a little melted dark chocolate over the frosting just before serving.