Although you're right that that energy is not spent cooking, it is helping to heat your home, and save you mental energy. Energy you can spend calculating how much energy you're actually saving.
You're talking about a couple hundred watts. You could cook non-stop for your entire life and you still wouldn't waste as much energy as a single flight with a modern airplane.
We're spending more just typing on our phones today, considering the phone, the inefficient charger left plugged in, the server of the platform we're posting on.
Try seeing of any of the lamps in your house can be upgraded to led. That could save you hundreds of watts for hours every day. (hundreds of watts per hour).
Go to work by bicycle, or train, or bus. (thousands of watts a day)\
LED's are awesome! I replaced my bathroom lights when I got into this apartment, that saved me 90 watts. And this may be unusual, but those are on for about 8 hours a day here