I received this as an email from the Florida Power & Light blog, and had to share because the answer was surprising:
Question: What uses the least amount of energy when cooking: a microwave, electric oven or slow cooker?
Answer: That’s an easy one. A microwave oven is typically your best cooking option if you’re looking to save energy. Let’s take a look at how microwaves compare to other cooking appliances.
Of course, to that I will add: For additional energy savings, make sure all of your appliances are Energy Star qualified.