A heat sink for cooling at least one electronic device package is provided. The electronic device package has an upper contact surface and a lower contact surface. The heat sink comprises at least one thermally conductive material and defines multiple inlet manifolds configured to receive a coolant, multiple outlet manifolds configured to exhaust the coolant, and multiple millichannels configured to receive the coolant from the inlet manifolds and to deliver the coolant to the outlet manifolds. The manifolds and millichannels are disposed proximate to the respective one of the upper and lower contact surface of the electronic device package for cooling the respective surface with the coolant.