Soak 1/2 cup raisins in 1/2 cup vodka for 10 minutes. Drain and reserve the vodka.
In a separate bowl combine 1 cup warm milk with the dried yeast and 1 teaspoon sugar. Set aside for 10 minutes until it is nice and foamy.
Combine 4 cups plain flour, 3/4 cup sugar and 1/2 teaspoon salt. Mix in the yeast mixture with the reserved vodka, the egg yolks and 1 teaspoon vanilla essence. Knead for 10 minutes. Knead in the butter as well.
Place in an oiled bowl, cover and set aside for 1 hour.
Preheat oven to 170°C. Punch down the dough. Knead in slivered almonds and raisins. Place in a greased bread pan. Cover and set aside for 30 minutes. Bake for 1 hour.
Cool the cake. Meanwhile combine the icing sugar and milk together to make a thick paste. Pour over the cake when just ready to eat.