Sift the flour with the baking powder into a bowl and mix carefully with the desiccated coconut. Cut the pineapple into small pieces. Mix the egg, sugar, oil, yoghurt and rum well. Add the pineapple pieces and mix in. Finally fold in the flour mixture. Pour the dough into the molds and bake until golden.
Let the muffins rest in the baking sheet for 5 minutes, then remove them from the molds and let them cool.