Method

• 1.
  Preheat the oven to 160°C. Grease a rose-shaped baking pan.
• 2.
  Cream butter and half the sugar in the bowl of an electric mixer until light and fluffy. Add egg yolks and beat until just combined.
• 3.
  Sift together flour, soda and baking powder. Place alternating spoonfuls of sour cream and dry ingredients into creamed mixture, stirring well. Add vanilla.
• 4.
  Whisk eggwhites until soft peaks form, then slowly add remaining sugar. Beat until stiff peaks form.
• 5.
  Add a little of the eggwhites to cake mixture to loosen, then fold in remaining eggwhites. Fill prepared pan and bake for 1 - 1 1/2 hours or until a skewer inserted into centre comes out clean.
• 6.
  Remove from oven and cool in pan for 5 minutes, then turn out on a wire rack to cool completely.
• 7.
  For the icing, combine icing sugar, colouring, rosewater and 3-4 tablespoons warm water until a soft dropping consistency. Add a little more water if necessary. Drizzle icing all over cake, allowing to drip down sides. Decorate cake with hyacinths and dust with extra icing sugar.