Preheat your oven to 195°C (175°C fan) and line a 10 inch springform cake tin.
In a small sauce pot melt the butter over low heat, remove from the heat, then stir through the caster sugar, cinnamon and salt until combined. Leave the mixture to cool for about five minutes before carefully whisking in the beaten eggs. Set aside while you prepare the cake batter.
In a bowl cream the butter, sugar, lemon zest, vanilla extract and almond extract together until pale, light and fluffy. Add the eggs, beating well.
In another bowl stir together the flour, ground almonds and salt.
With the mixer on low speed, alternate adding the flour mixture and sour cream, beginning and ending with the flour. Mix only until everything is combined.
Spread the batter evenly into the prepared tin.
Arrange the apricot halves cut-side facing up over the batter.
Pour over the cinnamon topping evenly over the fruit.
Bake for approximately one hour, or until a skewer inserted into the centre comes out clean. Keep an eye on it towards the end of baking, as the topping can make it difficult to judge doneness by appearance alone.
Allow the cake to cool in the tin for 30 minutes before carefully removing. Slice and serve.