The invention concerns a method for preparing foam from a milk-based alimentary liquid, including the successive steps of: a) spacing a quantity of alimentary liquid in a container associated with stirring members; b) heating said quantity of alimentary liquid to bring it in proximity to a first desired temperature level while mechanically stirring it at a first stirring speed, lower than the foam creating speed, and c) stirring said quantity of liquid at a second stirring speed, sufficient to make said liquid foam.