The word "ambrosial" origninates from the Greek word "ambrosia," which translates to "food of the gods".  This Greek word itself is derived from "ambrotos," meaning "immortal," and further back to the Proto-Indo-European root "mer-," which means "to die," hinting at the idea that ambrosia is something that gives immortality. 

The adjective "ambrosial" first appeared in English in the late 16th century.  The OED's earlies evidence of the use of the word ambrosial is from 1578.   It was derived from the Greek word "ambrosia," which meant "the food of the gods" or "immortality". In English, "ambrosial" initially meant "immortal, divine, of the quality of ambrosia". The sense of "fragrant, delicious" emerged later, around 1660. 

Examples of ambrosial used in a sentence: 
"The desert's ambrosial flavor reminder Alice of her childhood picnics." 
"An ambrosial sentence describes something as having a divine or exceptionally pleasing taste or smell, like the food of the gods." 
"The pastry was ambrosial, with a delicate balance of sweet and buttery flavors." 
"The honey had an ambrosial sweetness that was both intoxicating and soothing."
"The scent of the lilies was ambrosial, filling the room with a gentle fragrance."  
"Her jam was ambrosial, syrupy with honeyed fruit, and scented with elderflower," says Cambridge Dictionary. 

Just the facts:

AMBROSIA Definition & Meaning - Merriam-Webster

AMBROSIAL Synonyms: 107 Similar and Opposite Words | Merriam-Webster Thesaurus