Enriched Manna Biscuit

Enriched Manna Biscuit is a consumable that restores health and mana. Merideth Carlson came up with the idea of a special horse feed destined to nourish spiritual horses, primarily made out of enriched manna biscuits.

Source
Enriched Manna Biscuit is sold by Argent Quartermaster Hasana at The Bulwark, Argent Quartermaster Lightspark at Chillwind Point, and Quartermaster Miranda Breechlock in Light's Hope Chapel. You must be with Argent Dawn to purchase this consumable.

As a Quest Objective

 * Manna-Enriched Horse Feed (quest)