I've never eaten so well in my entire life.
non a-VE-vo mai man-GIA-to co-ZÌ BE-ne — stress on 've-', 'gia-', 'così', 'be-'. Sincere and enthusiastic.
After finishing a family meal — a generous, genuine compliment about the food that delights any Italian mother.
'Non avevo mai mangiato' uses the past perfect (trapassato prossimo) — 'never before had I eaten'. The hyperbole is culturally expected and warmly received. Food in Italian culture is love expressed — praising it praises the cook's care.
Questo ragù è il migliore che abbia mai assaggiato.
This ragù is the best I've ever tasted.
Specific dish compliment — more memorable than a general one
Sa cucinare meravigliosamente bene.
You cook wonderfully well. (formal)
Direct compliment to the cook — use 'lei' with older parents
Capisco ora da dove viene la sua passione per la cucina.
Now I understand where his/her passion for cooking comes from.
Credits the parent for the partner's love of food — very charming
Food compliments to Italian mothers are sacred. 'La cucina della mamma' (mother's cooking) is a cornerstone of Italian identity. Saying 'non ho mai mangiato così bene' is the highest compliment — it tells a mother her love has been tasted and appreciated.