Bargoed blitzed Llanharan 42-12, scoring six unanswered tries to maintain their one hundred percent record at the top of the Swalec Championship.
The first quarter saw the outside-halves swap penalties, with the away side edging it at 3-6 after 20 minutes.
Bargoed took the lead with a penalty try after multiple infringements from a five-metre scrum, making it 10-6.
The Blues extended their lead with a try by wing Lewis Protheroe but on the stroke of half time Bargoed lock Marc Gwilt got a yellow card for handling in the ruck. James Whittingham slotted his third penalty to make it 15-9.
Bargoed looked far more purposeful from the start of the second half and Prosser scored in the corner for Bargoed’s third try.
The best and bonus point try came on the hour. Prossser took the ball in his own half and sliced through the Llanharan midfield, before drawing the defence and putting centre Darren Humphries away to run in from 40 metres.
Two more tries came from Dafydd Carter, who scored out wide, and prop Lewis Lippiett crossed after great forward play in injury time. The win puts Bargoed four points clear at the top of the table with 20 points.
In other games on September 27 Blackwood lost 38-30 away to Tata Steel and Newbridge were beaten 16-43 at home by Cardiff Met.