Easy but you should not be scared of highness. Around 2/3 hours including the visit to the grotto. Do not forget a tourch ;-) Tobbacco grotto route in wikilog
A day hike if you follow this route but around 2 hours hike to the top if you depart from the basis of Camarasa damm. Then it would be 4 hours hike. Wikilog route to La Penalta