Abstract: The installation (1) comprises: a vacuum expansion chamber (4), having an inlet (4a) provided with a first gas-tight valve device (5) for receiving a flow of semi-finished pieces (3) prepared starting from a confectionery compound and including particles, such as air bubbles and/or powders, capable of causing an expansion thereof under vacuum, and an outlet (4b). In chamber (4) there is provided a rotating drum (7) having a grille structure, intended to receive and transfer to the outlet (4b) of said chamber (4) a flow of said semi-finished pieces (3), in a controlled period of time sufficient to allow an expansion thereof under vacuum. A cooling and conveying apparatus (10) under vacuum, at a controlled temperature, has an inlet coupled with the outlet of the expansion chamber (4), and an outlet having an associated second gas-tight valve device (18) for discharging the expanded and cooled confectionery products (3).