The present invention relates to a device for heating and/or frothing a beverage (19), including: a first duct (21) connectable to an upstream steam source and having a first valve (31) configured to be opened and closed and to enable or prevent steam flow into the duct; a second duct (22) connectable to the upstream steam source and having a second valve (32) configured to be opened and closed and to enable or prevent steam flow into the duct; mixing means (14), which are connected to a common point of the first and second ducts (21, 22), are located downstream of the first duct (21) and the first valve (31) and downstream of the second duct (22) and the second valve (32) and are arranged to introduce and mix at least steam into the beverage. The device further comprises a Venturi assembly (22a) configured to operate by Venturi effect in order to mix air with steam in one the two ducts when the other of the two ducts is closed. Thanks to the device of the invention, heated beverages can be obtained in considerably quick times. The invention also relates to a method for heating and/or frothing beverages, as well as to an espresso coffee machine including the device.