Paul Wilson, 38, was said to have been meticulous about his condition and asked for “no nuts” when staff at the Indian Garden, Easingwold, North Yorkshire, cooked his chicken tikka masala takeaway.
Wilson, a bar manager, was found slumped in the toilet at his home in Helperby in January 2014 and had died from a severe anaphylactic shock.
Restaurant owner Mohammed Zaman was convicted of gross negligence manslaughter following a trial at Teesside Crown Court, at which the jury was told he swapped almond powder in recipes for cheaper groundnut mix, containing peanuts, despite warnings.
The prosecution alleged Zaman, who owned six restaurants in York and North Yorkshire, was almost £300,000 (€388,000) in debt and cut costs by using the cheaper ingredient and by employing untrained, illegal workers.
Wilson died three weeks after a teenage customer at another of Zaman’s restaurants suffered an allergic reaction which required hospital treatment.
She had been assured her meal would not contain nuts.
The prosecution said the owner had “put profit before safety” at the restaurants he owned.
Zaman, from Huntington, York, denied manslaughter by gross negligence, perverting the course of justice, and six food safety offences.
He was found guilty of all charges except perverting the course of justice.
He claimed he left managers to run his restaurants and that included ordering stock and hiring staff.
He was not on the premises when the curry was sold.
Richard Wright, prosecuting, said Wilson had told staff his meal must be nut-free.
He said the restaurant had written “no nuts” on his order and on the lid of his curry.
Wright said: “Mohammed Zaman received numerous warnings that he was putting his customers’ health, and potentially their lives, at risk.
“Tragically for Paul Wilson, Mohammed Zaman took none of those opportunities and ignored all of the warnings he was given.
“His was a reckless and cavalier attitude to risk and one that we, the prosecution, would describe as grossly negligent.”
Wilson’s parents Keith and Margaret, from Sheffield, said their son had carefully managed his condition since he was seven when he had a reaction to a Marathon chocolate bar.
He loved curry but was always clear when ordering that his food must not contain nuts, said his mother.
Detective Inspector Shaun Page said Wilson’s death was “totally avoidable”.