Gardner spent part of last season on loan at Forest, and he became a key part of the Reds' team, catching the eye with his performances in the middle of the park.
The 23-year-old played 18 times for Forest in total, scoring four times, and he only has positive memories of his spell at the City Ground.
"There's nothing better than playing competitive football - winning games and getting that winning mentality," he said.
"My two loans helped me massively last season. Forest was a great loan move for me.
"The fans were great there and I got to live at home so it was a great part of my career and one that I look back on fondly.
"They're a massive club and they deserve to be in the Premier League in my opinion."
Gardner's career at Villa had stalled prior to his move to Forest, with the youngster struggling to find form and opportunities.
However, his impressive showings with the Reds convinced Tim Sherwood that he had a future at Villa Park and he was expected to play a big part for the Claret and Blues this term.
Unfortunately, things haven't gone according to plan for Gardner, and an untimely injury he picked up in pre-season has halted his progress.
Gardner has spent the entire campaign so far on the treatment table, but he is edging back to full fitness and will hope to play a big part for Villa in the near future.