cuocere is indeed very irregular
io cuocio = I cook
io cossi = I cooked

and, it is not exactly to bake = (I believe) to cook in the oven.

there is a relationship with biscotto = bis - cotto ( cookie) which literally means cooked twice.

Terra ferma = ground which doesn' move ( said from the sailor, in contraposition with the movement of the ship on the sea)

terra incognita = unknown land ( written, I suppose, in ancient maps)

(byb, ok about cotto and rotto, but notice that the first "o" is not pronounced in the same way in the two cases. One is open,an one is not)