"This is the only original recipe."
Translation:Questa è l'unica ricetta originale.
I think the use of "solo" is more like saying "alone" and "unico" means "the only one"
From Zanichelli Italian dictionary non si vive di solo pane (one does not live by bread alone). There is a phrase da solo a solo which means one to one: voglio vederti da solo a solo (I want to see you privately). You can say the same thing using the idiom a quattrocchi!