Actually there is cake in the game and you can get to it but you have to keep the companion cube with you will the end of the game and then you can find it.
Great game with an awesome humor. The fun of the game really is being ensnared by the story behind the setting (so much eeriness), and of course solving the puzzles. For those who thinks it's too easy, well, there's advanced levels, and the great big extension map pack based on the flash game, which is fairly more difficult. I still can't beat GLaDOS... I'm too slow, but it's the first 3D environment game I've ever played. Still love it though.