I've been really enjoying this simple rice cooker recipe for a baked fat omelet
http://justbento.com/handbook/recipe...mer-vegetables

My only alteration is that I add half a chopped onion to this recipe (red salad onion has been the best). Oh yes, and I add 4 eggs rather than 6 - even 3 big ones do the trick in my 5 cup rice cooker.

I tried making a Spanish tortilla de patatas with this method but it just didn't work out for me. For some reason it tasted bland - the baked 'frittata' recipe I linked to does need the grated parmesan for an umami kick.
I guess 'tortilla al horno' (baked tortilla) just isn't for me.