Preheat oven to 200C/400F/gas mark 6/Fan 180C.In a bowl, mix the flour, baking powder, bicarbonate of soda and salt. Stir in the grated carrot or courgette.Melt the butter then, in a separate bowl, mix it with the beaten eggs and yoghurt.Pour the wet mixture into the dry and mix together well. When well blended, split the mixture in two.For the Black Olive and Parmesan Muffins, stir the olives and most of the grated Parmesan in to one half of the mixture. Divide between muffin cases and sprinkle the remaining Parmesan on top.For the Toasted Seeds and Cheddar Muffins, place all of the seeds in a saucepan and cook over a medium to high heat until they start to brown and a few start popping. Mix the seeds and most of the grated cheese in to the other half of the muffin mixture. Divide between muffin cases and sprinkle the rest of the Parmesan on top.Cook for 18-20 minutes (or, as lovely Hugh says, until a toothpick comes out clean but don't worry if you don't happen to have a toothpick - the tines of a fork will do just as well. 'Tines' - a much under-used word, don't you think?)