Grind the eggs with the sugar very well. Add the softened butter. Grate the zest from 2 oranges and lemon , squeeze out from them juice.Get a Cup = 200 ml Linking the juice with eggs and butter, zest of lemon and orange. Stir. Put to boil in a water bath. I bet when the water doesn't boil. Cook stirring constantly with a whisk to not welded the eggs until thick. My process took about 15 minutes from the moment of boiling water. Cool and put in a convenient container.