For the milk cream strudel, cream the butter, powdered sugar, vanilla and lemon zest.
Gradually add the yolks. Stir the curd and sour cream until smooth and slowly add to the butter mixture. Beat egg whites, sugar and salt until creamy. Fold in snow and raisins.
Form 2 strudels, brush with butter and bake for 15 minutes at 165°C. For the royal, mix all ingredients and pour over the strudel and finish baking.