Apparatus for preparing and dispensing a beverage obtained from a concentrated fluid product having the taste of the beverage to be prepared, in a machine for preparing various types of coffee and milk based beverages, there being provided a steam generator (10), an apparatus (1) for producing coffee as well as a source (25) of liquid milk. The apparatus includes a tank (33) containing the concentrated fluid product to be used for preparing the beverage, a connector unit (34) connected to said tank (33), a pump (36) arranged so as to convey a predetermined quantity of concentrated product from said tank (33) to said connector unit (34), a water heating device (39) provided with an inlet (39a) and an outlet (39b) for the water and an inlet (39c) for introducing the steam, a water supply line (42) connecting the inlet (39a) of the said heater (39) to a water source (13), an intercept valve (43) arranged along said water supply line (42), a line (42a) for connecting together the outlet (39b) for the heated water from said heater (39) and said connector unit (34) so as to introduce into the latter a predetermined quantity of water, a steam line (40) connecting said generator (10) to said inlet (39a) for the steam, a valve (41) arranged along said steam line (40), a beverage preparation device (17) with associated dispenser (18) connected to said connector unit (34) and to said source (25) of liquid milk. The concentrated fluid product is in particular chocolate-based.