Sweet Potato Cornbread

had high hopes for this recipe - cornbread and sweet potato. Very easy to make, and baked it for 20 minutes (per recipe) and toothpick inserted came out clean. However, upon cutting it, it was way undercooked in the middle. The outside that was baked properly tasted ok, but nothing great. won't make this again, mostly due to the taste was not what I had hoped for