In the bowl of a large food processor fitted with an "S" blade, add in the black beans, cacao, sugar, almond butter, vanilla, and salt. Process until relatively smooth, then add 2 tablespoons of water to help it come together with a spreadable texture.
Taste the dip and adjust any seasoning to taste. For a frosting, you can add 1/4 cup more coconut sugar, if needed, or you can add more cacao powder for a darker chocolate flavor.
Serve right away with fresh fruit, or store it in the fridge where it will thicken up further. This can be kept in an airtight container in the fridge for up to a week.