1. Preheat your oven to 350 F (175 C). Grease and flour an 8×8 inch square baking pan, or line it with parchment paper, leaving an overhang on two sides to easily lift the cake out later.

2. In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt. Make sure there are no lumps and the ingredients are evenly distributed.

3. In a large mixing bowl, using an electric mixer, beat the softened butter and granulated sugar together until the mixture is light, fluffy, and pale in color. This usually takes about 2-3 minutes.

4. Beat in the eggs one at a time, mixing well after each addition until fully incorporated. Stir in the vanilla extract, then add the sourdough discard and mix until just combined. The mixture might look a little curdled at this stage, but don’t worry, it will come together.

5. Gradually add the dry ingredient mixture to the wet ingredients, alternating with the milk. Begin and end with the dry ingredients. For example, add about a third of the dry mix, mix until just combined, then add half the milk, mix, then another third of the dry mix, the remaining milk, and finally the last third of the dry mix. Be careful not to overmix; stop as soon as no streaks of flour remain.

6. Gently fold in the 1 cup of shredded coconut until evenly distributed throughout the batter. Pour the batter into your prepared baking pan and spread it evenly. Sprinkle a little extra shredded coconut on top if desired for a pretty finish.

7. Bake for 25-30 minutes, or until a wooden skewer or toothpick inserted into the center of the cake comes out clean. The top should be golden brown and spring back lightly when touched.

8. Let the cake cool in the pan on a wire rack for at least 15-20 minutes before attempting to remove it. Once slightly cooled, you can lift it out using the parchment paper overhang and transfer it to the wire rack to cool completely before slicing and serving.