The best temperature seems to be 190C with the fan on, until the top starts heading toward black.
Use small pans: the reactions you're looking for happen around the edges.
Try to keep the amount of water in the mash to a minimum.
Use a pizza stone/quarry tile if you can.
Leave room for the mash to swell.
Put something underneath the pans to catch stuff that boils over.
Stop once the top starts going really dark brown. (Although you don't have to. Some keptinis has traditionally been baked totally black.)
And, last but not least, don't worry too much about burning the mash. You get interesting flavours anyway.