With just 114 runs needed, Glamorgan reached their victory target with 19 balls and six wickets to spare with Sam Northeast top scoring with 44.
Glamorgan took control of the match inside the opening PowerPlay having put Essex into bat. Hogan and Neser were hugely impressive, combining to restrict the visitors to 14 for three at the end of the sixth over.
Will Buttleman showed attacking intent from the start of his innings, attempting to slog sweep Michael Hogan in the first over. Despite this aggression he never really got going and when he played his second big sweep shot off Hogan he was trapped lbw for 2 from eight balls.
It was also Hogan who claimed the second wicket with Rossington mistiming a pull shot that was caught on the boundary by Neser.
Michael Pepper had made a career best 75 not out in Essex last match in this competition, here he managed 3 from 10 balls before he drove the ball to Dan Douthwaite at mid-on off the bowling of Neser.
Things settled with the partnership between Paul Walter and Matt Critchley of 58 that brought Essex back into the match but when both fell in the space of three balls to Douthwaite it was Glamorgan who were back on top. Walter went to a ball that swung enough to take a edge through to wicket-keeper Chris Cooke. Critchley absolutely creamed a cut shot that was hit straight at Marnus Labuschagne who held on to the catch.
When Daniel Sams was run out and Simon Harmer was caught behind off Hogan from the very next ball Essex had gone from 72 for three to 81 for seven in the space of 10 balls.
Neser finished with career best figures of three for 13 as Essex finished on a disappointing 113 for nine.
Essex were giving some hope of defending this sub-par target when Glamorgan captain David Lloyd was dismissed by Daniel Sams for a four ball duck, but from there a string of partnerships anchored by Northeast that put Glamorgan in sight of victory before some big hits from Chris Cooke and Dan Douthwaite got the team over the line.
As with Essex’s batting efforts, it was Critchley who was the best performer for the visitors with the ball, finishing with one for 17 from his four overs with Simon Harmer also bowling a tight spell, but there was never enough runs on the board for them to squeeze out a victory.