Christensen spent two seasons in Germany from 2015, and made 80 appearances for the Bundesliga club across domestic competitions and the Champions League.
The 21-year-old has already made five Premier League appearances for Antonio Conte’s side since returning to Stamford Bridge in the summer, and is in line to start against Manchester City on Saturday with David Luiz suspended.
Chelsea have been criticised in the past for failing to develop a clear pathway between academy and first team, but Christensen, who joined the Blues in 2012, says the club’s pastoral approach is behind his success.
Asked about his time at Monchengladbach, Christensen told Chelsea’s official website: “They kept looking after me with videos, texting me every day with how I was doing.
“Eddie [Newton] and Paulo [Ferreira] did a great job with me. The club couldn’t have done any more with me than they did in terms of helping me in the right path.
Chelsea v Man City: Premier League match preview
“It was two seasons at a high level, facing strikers in the Bundesliga and two years in the Champions League as well, so I got a lot of experience. That was what I wanted.
“As a player you have to take responsibility for yourself and do what is best for you. You can’t expect people to do it for you. You have to perform when you get the chance.”