A first sixteen minute blitz of three goals from the home side made 3-0 at the break, with Clucas getting two and Roberts the other.
Roberts added another from the spot to make it six, after Gardner and Ryan had both scored.
The only consolation for the U's was the fact that the gap to safety remained at three points, with results going their way elsewhere.
The game started with the home side looking to get forward at every opportunity but it was the U’s who had the first sight of goal.
And it was only a great save by Tommy Lee that prevented Gavin Massey from opening the scoring in the third minute.
He cleverly moved the ball onto his right foot just outside the box and his low shot looked destined for the bottom corner until Lee’s intervention.
Thirteen minutes later, and the U’s found themselves on the end of a three goal salvo from the home side.
On six minutes, left back Drew Talbot had acres to look up and pull back for Gary Roberts to control on the bounce and volley past Chris Lewington.
The home side, gunning for a Play-Off place, then increased their lead on fifteen minutes, with a flowing passing move ending with a Spireites’ player in space to cross from the left once again.
This time it was Gardner but it was another pull back and an emphatic finish from Sam Clucas into the roof of the net.
It went from two to three less than sixty seconds later, as Clucas latched onto a through ball and dinked it over the onrushing Lewington to make it 3-0.
The U’s stemmed the tide defensively, albeit with the hosts taking their foot off the gas somewhat.
Alex Gilbey picked up a clever pass from Briggs down the left but his angled shot was well saved by Lee to preserve his side’s lead.
Gilbey then turned provider with four minutes to go until the break, setting up Chris Porter for the U’s best chance of the first forty five minutes.
Gilbey fed the U’s front man centrally but a shot was required a split second earlier than it came, giving Lee the chance to smother the clipped effort.
In the four or five previous matches, the U’s performed much better in the second half than the first but they had given themselves a mountain to climb at the Proact Stadium as they trooped in for the half time break.
Humes made all three substitutions at the break, with Healey, Brindley an Szmodics entering the fray, for Wynter, Lapslie and Murphy.
It didn’t get any better for the U’s after the break though, with Chesterfield coming out of the blocks sharp once again.
Three shots had already missed the target and Tom Eastman had cleared off the line before Gardner made it 4-0 on fifty eight minutes.
Morsy drove forward from midfield and a pass found Gardner, whose shot went through the hands of Lewington on its way into the back of te hnet.
Two minutes later, it was five as the U’s defence were split open by another incisive through ball which hallowed Ryan the chance to dink the ball over the diving body of Lewington.
The U’s tried to stem the flow forward and had a bit of joy, only in the fact that Chesterfield were happy to pass the ball around without really pushing men forward in great numbers.
The salt in the wounds came in the eighty third minute, as Roberts got on the end of another through ball and was upended by Lewington, who charitably was not punished more than the referee pointing to the spot.
Roberts took the spot kick himself and drove his effort firmly in to make it six.
It was a devastating night for the U’s but the consolation was that the gap to safety remained at three points, with results elsewhere not inflicting any further damage than the heavy defeat at the Proact Stadium.