A cooker, comprising: a planar structural layer; and a cooking surface layer extending over the planar structural layer to provide a cooking surface; characterised by: a liquid layer contained between the planar structural layer and the cooking surface layer; an elongate cooling channel, arranged such that in use liquid in the liquid layer flows into the cooling channel and out of the cooling channel into the liquid layer, the cooling channel being formed of a thermally conducting material (30, 32); and a first actuator controllable to raise and to lower a first region of the cooking surface layer and a second actuator controllable to raise and to lower a second region of the cooking surface layer thereby to generate a flow of liquid in the liquid layer, the first and second actuators being controllable alternately to raise and to lower the respective regions of the cooking surface layer in a predetermined sequence, thereby to induce a flow of liquid within the liquid layer, including a flow of liquid from the liquid layer into the cooling channel and a flow of liquid out of the cooling channel into the liquid layer. a planar structural layer; and a cooking surface layer extending over the planar structural layer to provide a cooking surface; characterised by: a liquid layer contained between the planar structural layer and the cooking surface layer; an elongate cooling channel, arranged such that in use liquid in the liquid layer flows into the cooling channel and out of the cooling channel into the liquid layer, the cooling channel being formed of a thermally conducting material (30, 32); and a first actuator controllable to raise and to lower a first region of the cooking surface layer and a second actuator controllable to raise and to lower a second region of the cooking surface layer thereby to generate a flow of liquid in the liquid layer, the first and second actuators being controllable alternately to raise and to lower the respective regions of the cooking surface layer in a predetermined sequence, thereby to induce a flow of liquid within the liquid layer, including a flow of liquid from the liquid layer into the cooling channel and a flow of liquid out of the cooling channel into the liquid layer. a liquid layer contained between the planar structural layer and the cooking surface layer; an elongate cooling channel, arranged such that in use liquid in the liquid layer flows into the cooling channel and out of the cooling channel into the liquid layer, the cooling channel being formed of a thermally conducting material (30, 32); and a first actuator controllable to raise and to lower a first region of the cooking surface layer and a second actuator controllable to raise and to lower a second region of the cooking surface layer thereby to generate a flow of liquid in the liquid layer, the first and second actuators being controllable alternately to raise and to lower the respective regions of the cooking surface layer in a predetermined sequence, thereby to induce a flow of liquid within the liquid layer, including a flow of liquid from the liquid layer into the cooling channel and a flow of liquid out of the cooling channel into the liquid layer.