Packaging (10) in flexible material, comprising a supporting base (11) wherefrom two opposite side walls (12) rise up, each one sealed to a half-perimeter (13) of the base (11) and sealed one to the other along respective side edges (14) and along the upper edge with a head sealing (16), characterised in that in an intermediate area of the packaging (10) at least one continuous transverse sealing (17) is provided, suitable for dividing the interior of the packaging (10) into two separate chambers, a lower chamber (20) and an upper chamber (21), suitable for containing two different components of a product to be heated and brought into contact at the time of consumption, said transverse sealing (17) being such as to open when a certain pressure is reached in said lower chamber (20), thus forming a single chamber inside the packaging (10).