The radiation left over from the Big Bang is the same as that in your microwave oven but very much less powerful. It would heat your pizza only to minus 271.3*C - not much good for defrosting the pizza let alone cooking it.
You know that I am living proof that the American Dream is real. Growing up our congressman cut through government bureaucratic red tape to help my mom buy our first house. That's the kind of congressman I'll be.