Air fryers, microwaves and slow cookers revealed as the most energy efficient ways of cooking as part of ‘Shop Smart, Cook Savvy’   Households reliant on oven cooking could save up to £604 per year by switching to a more energy efficient cooking method, according to new research by energy supplier Utilita. Joining together with frozen food specialist Iceland, the pair are embarking on a first of its kind partnership, that aims to help those struggling with the rising…