An improved efficiency cooling plate apparatus for full-scale clean fuel electric-powered aircraft having a cooling body including a plurality of bores, apertures and interior chambers working together to process and circulate fluid coolant and function as a heat sink device, interconnecting with the cooling system of an electric motor and cooperatively functioning to transfer thermal energy away from the electric motor using conduction, convection and radiation, while transporting heated fluid coolant away from heated motor components and to other components of a vehicle for further processing, then returning cooled fluid coolant into the cooling system of an electric motor, effectively partitioning heated fluid coolant, cooled fluid coolant, and electrical circuitry in a space saving design formed from a single part or minimal number of parts to reduce modes of failure and reduce required fasteners or connections to improve robustness and reliability while maintaining suitable aerodynamic characteristics.