A microchannel heat sink as well as method includes one or more microchannels through which a working fluid flows to remove heat from a heat-generating component, such as a microelectronic chip, and one or more recesses disposed in a surface communicated to the one or more of the microchannel to enhance heat transfer rate of the microchannel heat sink. The recesses can be located in a surface of a cover that closes off the microchannels. The one or more recesses can be located at one or more local hot spot regions to enhance heat transfer rates at the local regions as well as overall heat removal rate of the heat sink.