There is provided anaerosol-forming cartridge (220) for use in an electrically operated aerosol-generating system. The cartridge (220) comprises a base layer (222), at least one aerosol-forming substrate (224) arranged on the base layer (222) and comprising a liquid nicotine source, and an electric heater (226) including at least one heating element (236) arranged to heat the at least one aerosol-forming substrate (224). The base layer (222) and the at least one aerosol-forming substrate (224) are in contact at a contact surface which is substantially planar. The electric heater (226) and one or both of the base layer (222) and the at least one aerosol- forming substrate (224) are in contact at a contact surface which is substantially planar and substantially parallel to the contact surface between the base layer (222) and the at least one aerosol-forming substrate (224).
