Preheat the oven to 180C.
Either rub the zest of the 3 limes in with the sugar with your fingers, or take a shortcut and blast them together in a food processor.
Cream the butter, coconut oil* and zested sugar in a bowl until light and creamy.
Mix in the eggs, yogurt, juice of the 3 limes, then fold in the flour and baking powder. It will look curdled before you add the flour, but it will come together. Pour the batter into a greased/lined loaf tin, smooth the top, and bake for 45 - 55 mins until golden brown and a skewer/sharp knife comes out clean. A few crumbs attached is fine, but you don’t want to see any batter on the skewer/knife.
Mix in the eggs, yogurt, juice of the 3 limes, then fold in the flour and baking powder. It will look curdled before you add the flour, but it will come together. Pour the batter into a greased/lined loaf tin, smooth the top, and bake for 45 - 55 mins until golden brown and a skewer/sharp knife comes out clean. A few crumbs attached is fine, but you don’t want to see any batter on the skewer/knife.
Mix the icing sugar with the juice of the lime and drizzle over the top of the cooled loaf. If your lime is small, you may need to add a small drop of water to the mixture.
Scatter the crushed biscuits down the centre and finish by scattering with the reserved lime zest.
Leave to set before slicing to serve.