A plunger-driven delivery device for use with a feeding tube for delivering an ingestible material to a user is provided. The delivery device includes a device body having a first chamber, a second chamber and an exit orifice through which the ingestible material is delivered to the feeding tube. A first plunger is disposed in the first chamber, and a second plunger is disposed in the second chamber. The delivery device can be provided with the ingestible material disposed in the first chamber and a flushing liquid disposed in the second chamber. The delivery device is operable to provide sequential delivery first of the ingestible material and then the flushing liquid into the feeding tube. In some embodiments, a mechanical interlock is disposed between the first and second plungers to prevent use of the second plunger until the first plunger has been depressed. In additional embodiments, a first passage is defined between the first chamber and the exit orifice and a second passage is defined between the second chamber and the exit orifice. The second passage has a longer passage length than the first passage, allowing delivery of the ingestible material into the feeding tube before the flushing liquid is ejected from the delivery device. A method of delivering an ingestible material to a user through a feeding tube is also provided.