Well, you need a time keeper IC (such as DS1307), a temperature sensor (DS18B/S 20) and a microcontroller to read the data.
Next, you will need some interface. You say you want voice recognition ("on my command"). Your command can also be pushing a button. And the next problem of the interface is "make him tell".
A voice syntethiser chip may be available, but displaying the time/temp on an lcd/7 seg display is still a method of making it "tell" stuff.