Peel and boil the cassava until it is tender, adding a tablespoon of salt to the water.Take out of the water and puree.
2. Mash yuca
Add the butter, parsley and milk and mix well.Season with salt to taste and let cool down to room temperature.
3. Make balls
Put two tablespoonfuls of the mixture in the palm of your hand. Flatten it, put a cheese cube in the center. and roll around it into a ball.Repeat with the remaining yuca mash.
4. Coat balls
Whisk the egg. Dip the balls into the egg, then into the flour. Coat it with flour and shake off the excess.Chill uncovered for 2-4 hours (you can keep them frozen in a lidded container for a couple of days).
5. Fry balls
Fry in medium-hot oil (350 ºF [175ºC) over until they are golden brown.Place on a paper towel to drain excess oil.