The night before you plan to make the cake, combine the raisins and whiskey in a large jar and set aside to soak for about 12 hours, shaking it now and again.
To make the cake, sift the flour, baking soda, baking powder, cinnamon and salt in a large bowl. Set aside.
Grease an 8" round cake tin and preheat the oven to 180 C.
Beat the butter and sugar with a hand mixer or using a stand mixer, till light and creamy. Add the eggs and vanilla and beat again.
Add the yoghurt and the juice of half the orange (save the other half for the glaze). Mix well. The batter might curdle a little at this step, don't worry.
Add the flour mixture and beat it in slowly till combined. Fold in the soaked raisins with any whiskey left in the jar.
Tip the batter into the prepared tin, smoothen the top and bake for 50 minutes to 1 hour, until a toothpick inserted in the center comes out clean. Halfway through the baking time, rotate the cake tin and cover the top loosely with foil to prevent it from becoming too dark. Set aside to cool.
To make the glaze, melt the butter in a small saucepan on low heat, then add the sugar and mix till combined.
Pour in the milk and let the mixture simmer, then slowly pour in the orange juice (from the half orange leftover from the cake batter). Turn off the heat and add the whiskey. Mix well, and put the pan back on low heat.
Mix the cornflour with 2 tsps of water till dissolved and pour it into the pan. Bring the sauce to a boil and set aside to cool and thicken.
Pour the still slightly warm glaze over the cake. As it cools further, it will thicken and stick to the top. Slice the cake and dive in!
The cake will keep at room temperature for 2 to 3 days (in warm climates) and about 10 days in the fridge. Happy baking!