To you, obviously. That's kind of the point: your own consciousness isn't really what you think it is. Yes, I know that sounds really weird to the point of being a logical impossibility, but trust me: there's experimental data to back it up.
You is the thing (or, more accurately, the process) that is conducting this conversation.
> What is the "you" that is aware of (the rest of your brain's) decisions, that is observing your thought process?
But that is the whole point: you aren't actually aware of the rest of your brain's decisions. You think you are, but you're wrong. That is Dennett's thesis.
To back what up, exactly?
It seems like it'd be the next logical step: if consciousness is simply what (sensory) computations feel like "from the inside", then it stands to reason that other computations can also "feel like" something from the inside, regardless of the substrate they run on, no?
What evidence do you have of this? In fact, the majority of practicing philosophers are actually physicalists (56.5%):