Pre-heat oven to 180C/160C fan/gas 4.
Line the four mini loaf tins with a small piece of baking paper
Place the butter into a large bowl with the sugar, beat with an electric whisk for 3 minutes. Add the eggs, one by one, and then drop in the spice drops. Mix again – the mixture may split a little.
Sift in the flour and bicarbonate of soda. Add the salt. Using a metal tablespoon, mix everything together until all the flour is incorporated.
Add the mashed bananas and Greek yoghurt, mix well again.
Divide the mixture equally into the four tins. Sprinkle over the chopped pistachio kernels.
Bake for 30 minutes, or until a skewer comes out clean when inserted into the middle of the loaves.
Remove the tins from the oven, leave to cool and then transfer to a wire rack to cool before serving.
Notes: you can make this in a large, 1lb loaf tin. Bake for one hour and check that the banana bread is cooked through to the middle.
These will keep well in a tin for up to 3 days.