Death Pact

5th-level Necromancy
Casting Time: 1 action
Range: Touch
Components: VSM
Duration: Instantaneous

You reach out and touch an undead creature under your control. The creature immediately crumbles to dust, destroying it. You regain hit points equal to the current hit points of the undead creature. If this would cause you to recover hit points over your maximum, the rest is converted to temporary hit points.

Source: Homebrew