To make the layer cake
Grind the oats into flour. In a food processor, blend the flour with the rest of the ingredients, adding some water if you need to, until you get a heavy dough-like mixture that holds it’s shape when you press it between your fingers. It should also be easy to the whole thing into roll into a giant ball.
Roll out flat, about 1/4-inch thick, and cut into large circles with a cookie cutter: cake layers! The once I used was about 4 inches across.
Put the cake layers in the fridge until they have hardened up.
To make the frosting
Blend everything until smooth and thick, adding water as needed. You want it to have the consistency of frosting (duh).
Frost a cake layer, then add another on top, and so on and so on until you’ve used up all your cake or all your frosting.
Decorate as you like (I threw on some hazelnut butter instead of chocolate sauce since I used up all my cacao) and enjoy! This would be terrific with banana ice cream.