1.Combine seeds and milk in a small bowl; stand for 20 minutes.
2.Preheat oven to 180°C. Grease a deep 22cm round cake pan; line base and side with baking paper.
3.Beat butter, rind and sugar in a small bowl with an electric mixer until light and fluffy; beat in eggs, one at a time. Transfer mixture to a large bowl; using a wooden spoon, stir in sifted flours, ground almonds, juice and poppy-seed mixture. Spread mixture into pan; bake about 1 hour.
4.Meanwhile, make orange syrup: using a wooden spoon, stir ingredients in a small saucepan over heat, without boiling, until sugar dissolves. Bring to the boil; reduce heat, simmer, uncovered, without stirring, for 2 minutes.
5.Leave cake in pan for 5 minutes before turning, top-side up, onto a wire rack set over a tray. Pour hot syrup over hot cake; serve warm.
Lemon or mandarin flavours also blend with the taste of poppy seeds; substitute, in equal amounts, for the orange rind and juice given in the recipe. Store the cake, coated with syrup, in an airtight container for up to 2 days. The cake, without syrup, can be stored in an airtight container for up to 2 days, and can also be frozen for up to 3 months.