Firstly, I am a complete cake novice, so go easy
Bought a chocolate/orange mudcake 5 days ago. Store said it was baked that day. Half of it was eaten, then placed back into it's box (just cardboard) and stashed in my fridge.
I just rediscovered it then. Hence, it's been in my fridge for 5 days. Is it safe to eat? Should I take it out for a few hours to return to room temp first?
If you see no outward signs of spoilage and it smells fresh and good, eat it! I imagine it might have dried out on you though. Whether you return it to room temp or not depends on whether you like your cake cold or not. I personally like a cold slice of vanilla cake but prefer chocolate cake room temp.
I know my mudcake is good up to two weeks unrefrigerated, so I would think if it had been in the fridge it would be fine.