In the 1970s we used to run parties to sell some american pans you could stack the pans on top of each other while they where cooking to save power . Wealso used to cook a meat loaf and potatos in an electric unit and you used to place an egg in it as well to prove how gently it cooked .We also bake a sponge cake in a pan on the hob  can anyone remeber what they called these pans please