However, it was Chesterfield that began the sharper and, although the opening stages were tightly fought, carved out the best of a limited number of chances.
Kevan Hurst provided a dangerous cut-back from the byline, when it appeared the ball would roll out of play on the left, but his effort flew across the face of goal without the vital touch.
Chesterfield were frustrated again, from a similar situation, as Colin Larkin made progress down the right side of the box, but saw his low ball across the face of goal cleared by Ian Breckin.
Forest had to wait until the 20th minute for their first real opportunity as Grant Holt advanced beyond the full-back wide on the right before providing a dangerous ball to the far post. Neil Harris produced a clever knock-down for James Perch, but the midfielder lashed a low shot just wide of the post.
Chesterfield went close with a fine save from Paul Smith denying Hurst as he struck a dipping 25-yard shot which had threatened to sneak inside the post.
It was Forest that were to make the breakthrough however, as they found their cutting edge in the 35th minute. Nicky Southall's cross from the right was only partially cleared, giving Julian Bennett the chance to loft the ball back into the danger zone, where Harris provided a neat flick-on into the path of Jack Lester, who provided a simple, but confident headed finish from close range.
Larkin thought he had drawn the visitors level with a powerful close-range header, but Smith stretched out a hand at the last minute to block.
Barry Roche was also in good form at the other end, as he pulled off a fine double save to deny firstly Harris, after he had cut into the box, and then Southall from the rebound.
But he could do little in first-half stoppage-time as Southall provided the killer ball, firing a low cross across the face of goal. Lester failed to make contact on the near side, but the ball ran through to Harris, who made no mistake, lashing a powerful finish into the bottom corner from 12 yards.
Things quickly got worse for Chesterfield after the break as, within three minutes, the game was effectively all over.
Mark Allott was guilty of an obvious foul on Holt, as he turned neatly in the box, and the striker regained his feet to fire a confident spot-kick low to the keeper's right.
Chesterfield's misery was only increased as substitute Junior Agogo - making his Forest debut after signing from Bristol Rovers - set up a fourth, squaring a neat pass into the path of Southall, who struck a sweet curling, left-foot shot that found the top corner from 18 yards.