Fifteen Kilograms of Imperfect Lemons

This is very sweet!

Purée 800g cooked sweet potato, mix in 500ml orange juice, 12 egg yolks, and 360g sugar. Melt 350g butter and mix in. Beat 4 egg whites until stiff then mix into the sweet potatoes. Pour into a lined rectangular baking tray. Bake at 180 degrees celcius for an hour.