Preheat your oven to 350°F (175°C). Grease a baking pan or line it with parchment paper.
In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
In a large bowl, cream the softened butter and sugar together until light and fluffy.
Beat in the egg and vanilla extract until well combined.
Gradually add the dry ingredients to the butter mixture, alternating with the milk, mixing until just combined.
Fold in the desiccated coconut and raisins (if using).
Pour the batter into the prepared baking pan and smooth the top with a spatula.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Allow the Rasson to cool in the pan for about 10 minutes before transferring to a wire rack to cool completely.
Enjoy your meal!