Skipper Pablo Mills rounded off Saturday's League Two victory with a 20-yard strike as the Spireites had to play with 10 men following the dismissal of Drew Talbot.
Robins said: "At times that was some of the best football we have played this season. We have done well and we know we have a decent side, but it is just that belief, but we got that belief in front of goal today.
"I am delighted because I think Chesterfield thought they were going to come and turn us over, but I felt we controlled the game from start to finish.
"After Chesterfield's early miss, and you expect them to put chances like that away, I felt we took control of the game and our finishing was excellent."