A sponge pudding sparked an emergency at Royal Preston Hospital, say fire fighters.
Crews were called to the Avondale Unit at around 8pm on December 19 after a sponge pudding in a microwave overheated and caught light.
A spokesman for the fire service said: "We were called out after the plastic container on a sponge pudding overheated in a microwave and caught light.
"It was quite a severe fire although thankfully it was contained to the microwave.
"As it was contained, it didn't trigger the fire alarm but a member of staff noticed the problem, closed the door and called us out which was absolutely the right thing to do.
"If you smell smoke always make sure you get out and call us out."
Nobody was injured during the incident.
A fire service spokesman confirmed that the sponge pudding was completely destroyed by the fire.