She suffered irreversible brain damage from an asthma attack due to her nut allergy and died at Royal Blackburn hospital two days later on New Year’s Day 2017.
Owner Mohammed Abdul Kuddus, 40, and manager Harun Rashid, 38, were found guilty of manslaughter by gross negligence by a jury at Manchester Crown Court.
The judge, Mrs Justice Yip, warned the pair they faced going to jail when they return to court for sentencing on 7 November by Mrs Justice Yip.
She said: “The fact that I am granting bail shouldn’t be taken as any indication there should be a non-custodial sentence. You need to prepare yourselves for a custodial sentence.”
Megan’s family were in tears in the public gallery as the verdicts were announced.
The court heard one of Megan’s friends ordered the meal of an onion bhaji, a seekh kebab and a Peshwari naan, using the Just Eat website.
She wrote “prawns, nuts” in the comments and notes section to alert staff to allergies.
The meal was later found to have the “widespread presence” of peanut protein.
Following Megan’s death the restaurant was closed down by Trading Standards and environmental hygiene officers. It has since reopened under new ownership.
Peter Wright QC, prosecuting, told the court her death was a “disaster waiting to happen”.
Jurors heard there was a “litany of failings” in the kitchen including poor hygiene and no records of ingredients.
Rashid, of Rudd Street, Haslingden, was convicted of manslaughter, failing to discharge a general duty of employers under the Health and Safety at Work Act and breaching European Union food safety regulations. He had claimed he was merely a delivery driver at the restaurant at the time.
Kuddus, of Belper Street, Blackburn, was convicted of manslaughter. He had already pleaded guilty to the two other charges on behalf of himself and of behalf of the Royal Spice Takeaway Ltd.
Megan’s parents Adam and Gemma Lee said in a statement outside court: “Our lives will never be the same. The loss of our beautiful daughter has completely devastated us.
“Megan’s positive presence and infectious smile will forever be missed.
“It breaks our hearts that Megan didn’t get the chance to sit her GCSE exams, something she had worked so incredibly hard for, to celebrate her 16th birthday or go to the school prom with her friends.
“Megan didn’t get the opportunity to fulfil her ambition of working in musical theatre, to explore the world, fall in love or have children of her own.
“It’s these thoughts that cause great sadness, because nobody deserved it more than Megan.”
Mr Lee said: “Megan’s legacy is to be kind, considerate, to be helpful to others.
“We will continue to work with the Anaphylaxis Campaign to raise awareness of the dangers of allergies.
“Whilst we may have received some justice with today’s verdicts, we live in hope that today’s result is a warning to other food businesses operating in such a deplorable and ignorant manner to learn from this and improve their standards with immediate effect.
“We urge all food businesses to improve their standards in food safety and take allergies seriously.”
He added: “Do not guess, do not play ignorant, do not play Russian roulette with precious lives.”
Additional reporting by Press Association