Vegan Zabaglione: To a medium saucepan over medium heat, add the milk, sugar, starch, and butter. Whisk together and heat until steaming, then whisk constantly while the mixture thickens. Remove from heat once simmering and whisk vigorously to prevent clumps. It should have the consistency of a very thick pudding. Use an electric mixer if possible since it can get quite tiring. Allow to cool slightly, then cover the mixture with plastic wrap by nestling it directly on the mixture to prevent the formation of a 'skin' on top. Place in the fridge for at least 2 hours to overnight.
1 cup unsweetened almond milk, ¼ cup granulated sugar, ⅓ cup potato starch, 3 tablespoons vegan butter, 1 teaspoon vanilla extract
Blend: To a high speed blender, add the stovetop mixture, vanilla extract, 1 tablespoon of espresso, and solid coconut cream. Blend on high until creamy but do not overmix. Keep blending time under 1 minute at high speed if possible. You will likely need to use a blender tamper or stop to stir frequently since the mixture can be quite thick, especially at the start.
2 cups coconut cream
Espresso dip: To a wide bowl, add the remaining espresso and rum. Stir together. Fully submerge ⅓ of the ladyfingers in the mixture until soaked but not falling apart. See notes for more details. Then distribute them evenly along the bottom of an 8x8 inch baking dish.
1 cup espresso, 4 teaspoons dark rum, 24 vegan ladyfinger cookies
Layers: Add ⅓ of the mock mascarpone filling and spread it gently and evenly over the ladyfingers. Add another layer of ladyfingers, a second layer of cream, then a third layer of ladyfingers and the final layer of cream.
Chocolate topping: Cover snugly with plastic wrap and place in the refrigerator for 2 hours or overnight to set. The longer it sets, the better the flavors will meld and the cream will set. Before serving, dust the top with a layer of cocoa powder or chocolate shavings.
1 tablespoon cocoa powder