A special oven lamp rated at 300 ºC
They are always SES Small Edison Screw type
The voltage will depend on the country you live in
The Wattage is usually written on the glass - I think they come in 15W - 25W - 40W power levels.
http://www.lightbulbs-direct.com/contentimages/catalogimages/watermarked/oven-lamp-ses-365.jpg
Amazon sell them
Good luck...
Peccavi
February 2010