Complex sentence: From age 15 to 18, Catherine Spaak was the lead actress in at least twelve movies and, as a singer, was regarded by some as the Italian equivalent of French chanteuse Françoise Hardy, some of whose songs she recorded in 1963.
Split into simpler sentences: From age 15 to 18, Spaak was the lead actress in at least twelve movies. As a singer, she was regarded by some as the Italian equivalent of French chanteuse Françoise Hardy, some of whose songs she recorded in 1963.