Wash oranges and place them whole (unpeeled) in a large saucepan. Cover with water, bring to a boil, cover, and poach over low heat for 1½ hours or until peel yields easily when pressed with a finger. Drain and cool a few minutes.
Preheat oven to 180°C (350°F) and butter a 24 cm x 24 cm baking pan.
Cut oranges into pieces and remove seeds. Place in a food processor and purée.
In a large bowl, using a hand-held mixer, beat eggs and sugar. Beat in orange purée, ground almonds, and sour cream. Stir in raspberries using a spatula.
Pour mixture into baking pan and bake one hour or until a toothpick inserted into the centre comes out clean. Set aside to cool.
Beat together all the ingredients until smoothly blended. Ice cake and serve.