A drinking vessel is provided with a nesting reservoir system for containing and dispensing metered amounts of liquid beverage enhancer. Multiple metered doses can be dispensed, with multiple refilling of the drinking vessel. The concentrated enhancer is metered by the rotation of a knob that rotates a plunger mechanism into a reservoir volume chamber, with one rotation being calibrated to deliver a single dosage of liquid enhancer. All parts can be easily removed, cleaned and then re-used.