1. Preheat oven to 160C fan-forced (180C conventional). Prepare a 23cm bundt tin (approximately 6-cup capacity) by brushing liberally with the 15g butter,then sprinkle with the flour,rotating the pan so that the flour sticks evenly,then tap away the excess. Place tin in the fridge.
2. To infuse the milk with the saffron,lightly toast the threads in a small,dry saucepan over very low heat. After one minute,use a pestle or the back of a spoon to roughly crush the threads. Add the milk and heat gently without boiling. When hot,turn off heat and allow the saffron to infuse,and cool to room temperature. (If using turmeric,simply steep the powder in gently heated milk and set aside.) You will use 250ml for the cake and 25ml for the icing.
3. Sift the flour,baking powder and salt into a medium bowl,then stir in the almond meal. Set aside.
4. Place the butter,sugar and orange zest in the bowl of a cake mixer fitted with the paddle attachment and beat at medium-high speed until light – about 4 minutes. Add the eggs,one at a time,beating well and scraping down the bowl after each addition. Beat in the vanilla,then on low speed,add the sifted dry ingredients in three batches,alternating with the 250ml saffron or turmeric milk (the remaining 25ml is for the icing). Beat until just combined,again scraping the bowl to ensure even mixing.
5. Scrape the batter into the prepared tin and bake for 50-60 minutes,depending on your pan. To check if it is cooked,insert a skewer into the middle of the cake – it should come out clean. Remove cake from oven and place on a rack to cool a little (about 15 minutes) before inverting onto a plate to cool completely.
6. For the icing,stir together the 25ml saffron-infused milk,orange juice and icing sugar until it is a smooth,thin paste. Using a pastry brush,dab the icing liberally over the top of the cake,allowing it to drip down the sides.
Tips:There's no orange juice in the cake,just a little in the icing. The flavour comes almost entirely from the zest. Use a fine grater – a microplane is best – and avoid the bitter white pith.
Saffron pairs beautifully with orange,but it's the colour that I love here;a bright splash of it in a glorious cake does much to lift the spirits. If you don't have saffron,use turmeric.