The Academy graduate spent nine years with the club from the age of 12 and started in goal for the Blues in our back-to-back UEFA Youth League triumphs in 2015 and 2016.
But for all of the success he enjoyed with Chelsea, it was the care shown to him at a time of great difficulty which he remembers most fondly.
"My dad passed away during my time there and off the pitch, they were very good to me and my family and I thank them a lot for that," said Collins, who played for the Tykes in their Carabao Cup match at Stamford Bridge on Wednesday.
"It was a very strange feeling and I have never felt anything like that in my life before. Adi Viveash and Neil Bath helped my family a lot and helped with the funeral and things like that.
"From the age of 11 when I went there, my dad used to take me every day and dad grew a good bond with the coaches and they knew him very well."
Collins also told the Yorkshire Post: "It is not just on the pitch there, but off the pitch as well. They have such a variety of coaching staff who help in every aspect of your game. It is really good coming through at a place like that."