Bloodberry

Blood starts to siphon from a target you can touch, coalescing to create a number of Bloodberries equal to the damage dealt.

If the donor is unwilling, the target must succeed on a Dexterity saving throw or take 10 points of necrotic damage, taking half that on a successful save. 

At the end of the spell, the Bloodberries appear in the caster's hand.  A creature can use its action to eat one or more berries.  Each berry restores 1 hit point, and the berry provides enough nourishment to sustain a vampiric creature for one day. 

The berries lose their potency and dissolve if they have not been consumed within 24 hours of creation.

(credit to user-100508319 for original spell; revised to limit classes allowed.)