heating element for miniature working oven
Good old LEBs (light emitting bulbs) make great heaters.  They are quite inefficient at making light, but that's because most of the power gets converted to heat.

Incandescent bulbs aren't quite as available as they used to be, but you should still be able to get them.  Advantages are that they are intended to handle the heat, make nice indicators to show you when they're on, are obvious when they get blown out, and cool down rather quickly when power is removed.  Lighting up the inside of the oven while it's baking so that you can see what's going on inside is a nice extra.

Definitely include a interlock so that both terminals to the bulb sockets are shut off when the door is opened.  Some sort of over-temperature shutoff independent of the temperature controller is also a good idea.  Stuff happens, and you want extra redundancy so that no single failure causes harm.