Cook the yuca for 45-60 minutes until it is tender but not falling apart. Test one of the larger pieces. A paring knife should go through it easily without resistance.
Cut large, round pieces in half or thirds lengthwise. Find, remove, and discard the woody stem from all the pieces. The stems are in the center of the yuca.
Gently heat the olive oil and butter in a non-stick skillet over medium heat. Add the garlic. Cook for 45-60 sec.Take the skillet off the heat. Add salt, pepper, and parsley. Stir well.