1. Preheat oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.

2. In a large bowl, beat butter and granulated sugar together until pale and fluffy, about 3 minutes.

3. Beat in eggs one at a time, scraping down the bowl after each addition.

4. In another bowl, whisk together flour, cocoa powder, and salt.

5. Gradually add the dry ingredients to the wet mixture, mixing on low until just combined.

6. Pour the thick batter into the prepared pan and smooth the top.

7. Bake for 40 to 45 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.

8. Cool in the pan for 15 minutes, then transfer to a wire rack to cool completely.

9. Just before serving, dust generously with confectioners' sugar and sprinkle with toasted coconut.

10. Slice and serve at room temperature.