Likewise, Teemu Pukki levelled the game ten minutes before the break, capitalising on a mix-up in the away side's defence but timing his run well.
Yet Watford well and truly came alive in the second half and once Ismaila Sarr netted from close range to score his second of the season, the game never seemed in doubt.
That result gives Watford their second win of the season, as well as providing the Hornets with their first away points and goals.
They move up to 12th, whilst the Canaries sit rock bottom and still pointless this season.
Watford's front three come alive
Having not scored in their last three fixtures, you would have been forgiven for expecting yet another quiet performance up top from Watford.
The confidence on display from the front three has been apparent at moments, but finishing and substantial creativity has not reached a level which would be appealing to Watford manager Xisco Munoz.
Yet when Dennis backflipped away after putting the Hertfordshire-based outfit 1-0 up, things felt like they could be different.
The Sarr and Dennis link-up on the wings has potential to frighten Premier League defences, as it proved Saturday. The pace from both allowed them to get through and behind the Canaries' defence throughout.
Sarr will no doubt be guaranteed a big move at some point in his career. If he becomes a prolific goalscorer this season, paired with his high levels of creativity and pace, he will be the most important asset to the Golden Boys this year.
Despite not getting his name on the scoresheet, Josh King was nonetheless at the heart of a lot done in the 3-1 victory and you feel as though one goal could put him in strong form as well.
More experience = more success?
Despite a risky approach, it appears to have paid off. Cleverley captained the side well and Foster appeared to have a good level of command over the defence for much of the game.
Other more experienced players also made their mark - Danny Rose was superb at left-back and very nearly got an assist to his name with a beautiful through-ball to Sarr at the end of the first forty-five.
That being said, a mix-up between Foster and Craig Cathcart allowed Pukki to calmly slot home to provide Norwich's only goal of the game. The defence will continue to be prone to making mistakes.
Something needs to change at Carrow Road
Although Watford executed their game plan well, they were certainly not superb, and the odd defensive error might well have cost them as we saw with Pukki's goal.
For Norwich, however, they look poor at the back, lacklustre in attack, with not much about them at all.
Despite good movement from Dennis for the opener, the Norwich defence stood still and did not see him cut across them.
Watford's third stemmed from a woeful attempted clearance from Kenny McLean which went behind him and fell straight to the feet of Cleverley before King was put through.
Indeed, for once, Watford managed to usurp the opposition in terms of finishing - 8 of their 12 shots were on target while Norwich only had 5 on target from the same amount.