I'm sure others will chime in but here is my initial thought:
1. Remove oven door
2. Once bread is in place, cover oven opening with a sheet of thermal glass.
3. Light with three soft sources: one left, right, and top. Soft sources out of the angle of reflection of the glass.
4. Shoot your time lapse.
Plus, mount an angled mirror in the oven, high and to the rear, out of view in the frame. With that, you can use a small instrument (maybe a little 100w or 200w fresnel) and shoot it into the mirror to give the bread some nice backlighting.
One clarification, though... you are BAKING this bread, right, with a hot oven? Your post says "bread rising in an oven"... and bread rising and bread baking are two very different things. If you're just wanting to see dough rising, that's a lot easier, since you don't have to have a screaming hot oven, just a sort of warm environment. You wouldn't have to use a real oven for that... you could easily build a little oven set that would suffice and allow you more creative lighting. If you're doing real baking, then yes you need an oven.
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