In the eighth minute he showed all his class to twist the ball on to his left foot, before drilling a low drive in off the near post for his fourth goal since joining the Spireites in early January.
Macclesfield responded quickly and on 15 minutes John Rooney turned neatly in midfield before picking out Ahmed Deen with a pinpoint pass.
The left-back then delivered a slide rule cross for Gareth Evans to head home his 12th goal of the season from six yards.
Gritton might have added another for Chesterfield on 32 minutes when he pounced on a loose ball in the box only to fire a 15-yard drive two feet wide of the far post.
Rooney showed a moment of inspiration reminiscent of his older brother on the strike of half-time when he turned his marker inside out before lashing a 25-yard drive off the underside of the crossbar, the ball bouncing across the goal-line before Chesterfield made a desperate clearance.
Macc midfielder Jamie Tolley warmed the hands of Chesterfield keeper Tommy Lee in the 58th minute with a stinging drive from the edge of the box and just two minutes later sub Emile Sinclair could have scored with his first touch, instead blazing a 20-yard shot over the bar.
Chesterfield went close on 75 minutes when Aaron Downes sent a far-post header over the crossbar, Downes going even closer two minutes later when his opportunist nod from the six-yard line was brilliantly clawed away by keeper Jon Brain.
In the closing stages Gritton powered a drive over the crossbar as Chesterfield failed to press their claims for the last play-off spot.