Preheat the oven to 180ºC/175ºc fan.
Grease the cake tin with melted butter and dust with plain flour.
Optional for decoration - Cut a slice of lemon and cut that into the quarters. Dab with kitchen paper and dust with flour Place in the bottom of the star.
In a stand mixer or by hand, cream the butter at room temperature and sugars until pale and fluffy.
Add the eggs one at a time and mix together.
Mix in the yoghurt.
In a separate bowl, measure and sieve out the flour, bicarbonate of soda, salt and the mixed spices.
Sieve in the flour gradually and stop when the flour is evenly mixed in.
Divide the mix into tin. Over the lemon slices if you've added them.
Bake for 10-15 minutes until golden brown and a skewer comes out clean.
Leave in the tin for a few minutes to cool slightly and remove to cool completely on a wire rack.