The dough is too firm.
Add more liquid.
The food does not rise sufficiently in the oven.
Add more liquid.
Reduce the proving temperature.
Add the moisture much earlier on in the cooking process. Ideally, you should pre-heat the oven before placing the food inside and then release a burst of steam straight away (if your oven supports this function).
Add more yeast so that the food rises more. If you are using a bread mix shortly before its best-before date, add extra yeast.