There is provided an aerosol-forming cartridge (220) for use in an electrically operated aerosol-generating system. The cartridge (220) comprises a base layer (222) and at least one aerosol-forming substrate (224) arranged on the base layer (222) and comprising a tobacco- containing material with volatile tobacco flavour compounds which are releasable from the 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.