The 20-year-old is proving a sensation at Stamford Bridge after bagging his second goal for the club in Saturday's 3-2 win over Norwich City.
It has been a long road to the Blues first-team for Mount, who joined the club in 2005 at the age of six.
Mount was 18 years of age when he signed with Vitesse, but his senior career could have started earlier if Clark had had his way.
The former Newcastle and Fulham midfielder took over Scottish Premier League side Kilmarnock in 2016 and attempted to sign the English teenager after scouting his performances for Chelsea's youth team.
However, Clark told Tribalfootball that the west London club refused to sanction a loan deal.
"I think he was only around 16, 17 at the time, but Chelsea weren't interested in loaning him out at such a young age. Whether they thought Scottish football at that time was the right place for him anyway was another thing.
"I caught a glimpse of him when I'd been down south watching a couple of youth cup games when they went on to win the competition. You could tell even at that age that he was going to make something of himself, he is just a fantastic player."
Now in his second season under Lampard, Clark added that Mount was in the perfect situation to develop as a player.
"And what he has done is grow in stature and what Chelsea have done in terms of his development has been perfect - sending him to Derby with Frank, with him being that type of player as well, he learnt from the perfect role model as a player and an individual."