Tthe Italian was fired by the Hammers at the end of last season, a decison which the 22-year-old Collison found hard to take.
"He was the one who gave me my big chance and I feel like I owe him a lot," said Collison on Soccer AM.
"He took an interest in a lot of the young lads and for me it was great learning off someone like him because he wasn't a bad player, was he?
"He could still play.He joined in during training and some of the stuff he would do was pretty unbelievable. The first day in training we were playing two touch; he got the ball, flicked it round the corner and dinked Rob Green. Everyone just stood there and was like 'whoa, what have we got here?'
"He was really good. After training sometimes he'd take the boys for a one-to-one session which was nice to see from a manager, you don't always get that.
"He took a real interest. He let all the boys go out there and express themselves, which was nice. It's just a shame what happened."
Collison - who last featured for the first team in February - recently underwent an operation to solve a long-standing knee problem, from which he expects to return at the beginning of 2011.
"I'm hoping to be back around Christmas time," he confirmed. "I had an operation about four months ago to stabalise my knee cap and to have a bit of a tidy up."