The invention relates to an apparatus for aerating a pasty product. The apparatus comprises a housing (1) with an inlet (4) for the pasty product to be aerated and an outlet (5) for the aerated product. The apparatus comprises at least a first set of a rotor and a stator (21) and a second set of a rotor and a stator (22). The apparatus further comprises a gas injector (6) for injecting, upstream of the first set of a rotor and a stator (21), a gas into the pasty product to be aerated. The apparatus further comprises an intermediate mixing chamber (7) provided in the housing between the first and the second sets of a rotor and a stator (21, 22). A secondary product introduction means protrudes into the intermediate mixing chamber (7) so as to issue into said intermediate mixing chamber (7). A method for aerating a pasty product is also provided.