A heater assembly for an aerosol-generating system is provided, including: an electrically insulating support having an aperture； an electrical heating element disposed across the aperture in the electrically insulating support, being configured to heat a liquid aerosol-forming substrate to form an aerosol, and being substantially flat； capillary material, wherein a portion of the capillary material is in contact with the electrical heating element, and the capillary material is configured to convey the liquid aerosol-forming substrate to the electrical heating element； and two electrical contacts respectively connected to ends of the electrical heating element, the two electrical contacts supported by the electrically insulating support. An aerosol-generating system including an aerosol-generating device and a cartridge is also provided.
