Texture problem with marinated chicken I made a simple chicken marinade from a Nigel Slater recipe the other day: some olive oil, maple syrup, soy sauce, chilli flakes. I marinaded it (1 piece of boneless chicken breast) overnight. When I cooked it, it had tons of flavour but it was too soft. 

How can I marinade a piece of boneless chicken breast so that I get tons of flavour but it isn't too soft?

The piece was frozen and then thawed in hot water. Not sure if that's relevant.
You said thawed in hot water. That is the problem. Thaw in cold water or in the fridge overnight. Using hot starts cooking the meat. I would also suggest searing the meat on both sides and then cooking at 400 until it temps 155, then pull it and let rest for 10 min. The resting will allow the temp to hit 160.