The Under-18s had opened the campaign with a 28-15 win over Cardiff Blues Under-18s and backed that up in some style in the second game at Ystrad Mynach on Wednesday evening.
Wales Under-18s star Rosser, brother of first team ace Jared, got a treble and Brodie Coughlan, Will Reed, Dylan Davies, Matthew Jeffries and Lewis Bates all crossed the whitewash.
Timeline:
04m Coughlan t 5-0
06m Rosser t Reed c 12-0
11m Reed t Reed c 19-0
15m Rosser t Reed c 26-0
26m Davies t Reed c 33-0
29m Dodd t 33-5
35m Rosser t Reed c 40-5
42m Hawkins t Hawkins c 40-12
58m Hibberd Hawkins c 40-19
51m Jeffries t 45-19
67m Bates t Morgan c 52-19
74m Key t Hawkins c 52-26
Dragons:15 Jake Morgan, 14 Ewan Rosser (Richards 39), 13 Ollie Lewis, 12 Anuerin Owen (Paynter 39), 11 Lewis Bates, 10 Will Reed (Jones 59), 9 Dylan Davies; 1 Henry Hibbs (Wakeley 49), 2 Brodie Coghlan (Dowse 49), 3 Owen Peddle (Gibbons 51), 4 Joe Peard, 5 Ben Carter (Torjesen 57), 6 Matthew Jeffries, 7 Oli Howard (Coope-Franklin 51), 8 Benji Hoppi
Replacements: 16 Jack Wakeley, 17 Aaron Dowse, 18 Clay Gibbons, 19 Ben Torjesen, 20 Joe Coope-Franklin, 21 Jonny Paynter, 22 Morgan Richards, 23 Cian Jones
Dragons Under-16s Red (formerly known as North) lost 68-0 to Cardiff Blues Under-16s North.