Her first record came out in 1953, with a preface by Maurice Chevalier, who gave Nicole (then, age 20) the nickname "Le Petit Radiguet de la Chanson," meaning "The Small Radiguet of the Song" (after Ramon Radiguet, the French Modernist author). Chevalier was basically commenting on the maturity of Nicole's lyrics. Her simplistic, youthful voice conveyed a wisdom beyond her years and distinctly contrasted the yé-yé girl "Lolita" phenomenon that became popular in France a decade later. (Don't get me wrong- I enjoy that music, too.)
I can't find much information about Louvier online, and certainly nothing in the English language. From what I can discern, she eventually moved to a Kibbutz in Israel where she continued writing, and shared her time between Israel and France. She died in 2003 and is currently buried in Paris.