In a large bowl, combine all the wet ingredients for both chocolate cake layers using a hand mixer (eggs, milk, coconut oil, and sourdough discard).

In a separate bowl, blend together all the dry ingredients – sugar, flour, baking powder, and cocoa powder. Stir them well to ensure the baking powder and cocoa powder are evenly distributed throughout the flour.

While mixing at a low speed, gradually add the dry ingredients to the wet mixture. This will create a smooth cake batter.

Pour half of the prepared batter into a 9x13 inches (about 23x33 cm) baking dish lined with parchment paper.

Bake it at 350°F (about 178°C) for 10 minutes. Remember, this step won't fully bake the layer; the goal is to bake it just enough so it becomes solid, allowing you to add the filling and the second layer on top later.

While the first cake layer is baking, prepare the filling. In a large pot, bring the milk to a boil. Once boiling, reduce the heat to low and gradually add the semolina flour, stirring constantly to avoid lumps. Cook this mixture for about 5 minutes. After removing it from the heat, stir in the shredded coconut until it's fully incorporated into the mixture. The filling should have a thick but spreadable consistency.

Once the first cake layer is baked, spread the filling evenly over it. Then, pour the remaining half of the cake batter on top of the filling. Place the assembled layers back in the oven and bake for 20 minutes at 350°F (approximately 178°C).

While the dessert is cooling, prepare the chocolate glaze. First, gently heat the coconut oil on low heat until it's liquid and warm enough to melt chocolate. Roughly chop the chocolate and add it to the coconut oil. Melt them together over low heat, stirring until you achieve a smooth glaze.

Pour the glaze over the dessert, spreading it as evenly as possible. It's not necessary to let the cake cool completely for this step; it's sufficient if it's just warm, not very hot.

Allow the dessert to cool to room temperature so that the layers set, making it easier to cut neatly. If you want to speed up this process, you can place it in the fridge for an hour or two.

These chocolate coconut cake squares can be served in two ways: as finger food or as a plated dessert. For a bite-sized treat, cut them into smaller squares. If you're serving them as a sweet ending to a meal, cut them into larger pieces and plate them individually.