1. CUSTARD: Combine the custard powder and sugar in a small saucepan; gradually stir in the milk. Cook, stirring, until mixture boils and thickens. Remove from heat, stir in butter and vanilla. Press a piece of plastic wrap over the surface of the custard to prevent a skin forming; Refrigerate until cold.
2. Preheat oven to 170°C (150°C fan-forced). Grease a deep 22cm springform cake pan. Line base and side with baking paper.
3. Beat butter, rind and sugar in a large bowl with an electric mixer until light and fluffy. Beat in eggs one at a time. Gradually fold in combined sifted flours, orange juice, then almond meal.
4. Spread two-thirds of the cake mixture into the prepared pan. Dollop small spoonfuls of custard over cake mixture. Spoon the remaining cake mixture over custard: carefully spread with spatula to completely cover the custard. Sprinkle over raspberries, then flaked almonds.
5. Bake for about 1 hour 25 minutes or until cooked when tested. Cool cake in pan. Transfer cake to cake stand and dust with sifted icing sugar. Serve with thickened cream, if desired.

Suitable to freeze. Not suitable to microwave.