Sam Cosgrove scored twice as Aberdeen thrashed St Mirren in their biggest league win since March.

Cosgrove's header was his first for Aberdeen after 16 goalless games and just his second career goal.

Teenager Connor McLennan, on his first start, made it two with on-loan Derby defender Max Lowe scoring a third before the break.

St Mirren keeper Samson was culpable as Cosgrove doubled his tally, before Simeon Jackson chipped a consolation.

After scoring just five goals in seven league games, the Dons hit the net four times despite missing attackers James Wilson, Stevie May and Niall McGinn.

For last season's Championship winner St Mirren, it is now six defeats in eight games.

Aberdeen find their shooting boots

Derek McInnes has been accused in the past of not giving youth a chance. But with injuries and Scott McKenna's suspension limiting his options, the Aberdeen manager had six players who have come through the Dons youth system in his squad, including McLennan, who was making his first start a day after his 19th birthday.

Another young player who has had a difficult beginning to his Aberdeen career is 21-year-old Cosgrove. But his long wait for a goal finally ended when Shay Logan picked him out at the near post, and he stooped low to head beyond Samson.

Before that, Aberdeen had dominated possession without doing much. But as the pressure lifted from Cosgrove's shoulders, so too did it from Aberdeen as a whole. Gary Mackay-Steven cracked a shot off the far post, shortly before McLennan found the roof of the net with a delightful finish from outside the area.

While Aberdeen had their tails up, St Mirren looked a side bereft of confidence, and their afternoon got worse when new signing Adam Hammill had to exit early when he fell awkwardly on an arm after tussling with Graeme Shinnie.

Aberdeen have struggled for goals this season, but Lowe became the third player in a red shirt to net his first for the club as they continued to pour forward. The full-back started the move on the left hand side, then with the help of Mackay-Steven he raced into the box and collected the through ball before knocking it in.

Dons goalkeeper Joe Lewis almost gifted St Mirren a goal when his clearance clattered off Jackson and looped over him, but he managed to claw the ball off the goal-line. And Lee Hodson curled over as the visitors showed more life after half-time.

But they shot themselves in the foot when Cosgrove's effort was straight at Samsom with the goalkeeper failing to hold it as it fell into the net behind him.

The Paisley side did pull one back through a mistake from the hosts, when Stephen Gleeson's poor pass to Andrew Considine was seized on, and Jackson dinked the ball over Lewis. But it was a mere consolation, with St Mirren conceding four goals at Pittodrie for the second time this season.

Connor McLennan (right) watches as his shot hits the net to put Aberdeen 2-0 ahead

Worrying times for St Mirren - analysis

BBC Scotland's Jane Lewis at Pittodrie

Aberdeen had bemoaned their lack of goals recently and, with key attacking players missing, there was a worry their threatening intent would suffer. But there was little to worry about.

And that's what may well please the Dons manager McInnes the most. Despite missing a number of players, Aberdeen played with flare and confidence, with their wide play at times exciting to watch.

When Cosgrove grabbed his first goal for the club, there was no stopping the Dons. Constant attacking display, they were cruising and in control, and St Mirren had no answers.

While Aberdeen will go into the international break full of confidence, St Mirren have plenty to ponder, and plenty to work on. Already you fear it's worrying times for the Oran Kearney's side.

Post-match reaction

Aberdeen manager Derek McInnes: "There are loads of positives for me. For Sam Cosgrove to get his two goals, young Connor McLennan - fantastic goal - Lewis Ferguson back on the pitch, and the form of young Max Lowe. In spells we were very good today. I couldn't be more pleased."

St Mirren manager Oran Kearney: "We came here with a game plan and I think for 25 minutes we've executed it pretty well, and we're quite happy and content with how its going. Then all of a sudden in a flash of three minutes we find ourselves with an uphill struggle. It's tough and the players care as well I think - that's the important thing."