Grease a dome-shaped cake pan with unsalted butter and dust lightly with flour. Preheat the oven to 350°F (175°C).

In a mixing bowl, cream together unsalted butter and granulated sugar until light and fluffy, about 3-5 minutes. Add eggs one at a time, mixing well after each addition, followed by vanilla extract.

In a separate bowl, whisk together all-purpose flour, baking powder, and salt. Gradually add dry mixture to the butter mixture, alternating with whole milk, until just combined.

Pour half of the fluffy batter into the prepared pan, dollop raspberry preserves over it, then top with remaining batter and swirl preserves gently.

Bake for 45-55 minutes, or until a toothpick inserted comes out clean. Cool in pan for 10 minutes, then transfer to a wire rack to cool completely.

Once cooled, brush the surface with water or simple syrup and press shredded coconut all around the cake. Dust with powdered sugar just before serving.