A liquid-containing paperboard laminate carton including a one-piece plastic spout (1) having a pair of opposing flanges (4,6) sealed about an aperture (5) in one of the carton walls to both the innermost (26) and outermost (2a) surfaces of the carton wall. The double flange configuration not only forms a mechanically positive innerlock between the plastic spout and the carton wall, but even more importantly, isolates the cut edges of the aperture from exposure to liquid either from within the container or from the environment through which the carton must pass from the point of manufacture until it is ready for disposal after its contents have been consumed. The spout preferably includes a liquid passageway having a membrane-type seal (1c) across its discharge orifice to provide evidence of tampering and a resealable closure member (1b) such as a screw cap or a snap-on closure held in place by means of a mating ring or groove on the spout. The cross-sectional area and configuration of the liquid passageway and discharge orifice in the spout are designed to prevent to complete blockage by liquid when the package contents are being dispensed during a normal dispensing cycle, i.e., when the package is not being held completely upside down. Method and apparatus for securing said one-piece spout in sealed liquid type relation of both surfaces of the carton wall either sequentially or simultaneously are also disclosed.