In a large heavy bottomed stainless steel saucepan combine the lemon juice, sugar, yolks, eggs, and butter. Over high heat whisk the mixture constantly until thickened. Strain it into a bowl set over ice and chill it stirring to thicken slightly. Fold in the whipped cream and pour or pipe into paper cones to the top, and set in a rack to hold them. Freeze overnight. Peel off the paper cone and serve.