If your ube purée isn't ready yet, then boil the peeled, cubed purple yam until soft (about 15–20 minutes), mash it, and let it cool completely.
Then mix the Greek yogurt and the light mascarpone (or the ricotta) until smooth.
Next, add the cooled ube purée, the ube powder (if you use it), the maple syrup, and the vanilla extract, and also mix until smooth.
Dip the ladyfingers one by one into the cooled coffee only for a moment, and then line the bottom of a dish or small glasses with them.
After that, spread half of the cream on top, and then repeat the layer with the remaining ladyfingers and cream.
Cover it and put it in the fridge for at least 4 hours, but preferably overnight, so the layers can come together.
Before serving, sprinkle it with cocoa powder and, if you like, also with toasted shredded coconut.