Preheat the oven at 350F.
Peel and grate the yucca with the finest side of your grater. Put the yucca in a clean towel or kitchen cloth, and squeeze to get rid of all the liquid. Do this with enthusiasm and all your stamina, because a wet yucca will not render good results. You should have about 8 oz. of grated yucca.
In a bowl, cream butter and sugar until very pale.
Add eggs, one by one, beating well after each addition. Scrape the sides of the bowl every now and then, to make sure all the ingredients are mixing well.
Add yucca, milk, salt, baking powder, lemon and orange peel.
Pour the dough in 4 small ramekins or soufflé dishes, or one mini loaf pan, buttered.
Bake for 30 – 35 minutes. The cakes should rise and be lightly golden.
Turn off the oven, take out the cakes and let cool in a rack.
To unmold, run a knife around the borders, turn the cakes up-side down, and they will release easily.
To serve, put on a plate, add a scoop of mango sorbet on top (it could be another flavor of your choice), a mint sprig, and some black currant marmalade (optional). Serve at once.