Preheat the Oven: Preheat your oven to 180 degrees Celsius (350 degrees Fahrenheit) and line a round oven-proof dish with baking paper.

Prepare Blueberries: Place 1 cup of blueberries into a colander or strainer and cover them with Maizena (cornstarch). Set them aside.

Cream Butter and Sugar: In a bowl or using an electric mixer, cream together the melted butter and white sugar until the mixture is smooth and creamy.

Prepare Wet Ingredients: In a separate bowl, crack the eggs, pour in the milk, and add the vanilla essence. Mix them together and then add them to the creamed butter and sugar.

Fold in Blueberries: Add the 1 cup of Maizena-coated blueberries to the mixture and fold it together gently.

Add Flavor: Stir in the lemon zest, and give it one final gentle fold.

Bake: Pour the batter into the prepared oven-proof dish and bake in the preheated oven for 30-40 minutes. Check for doneness by inserting a toothpick into the center of the cake; if it comes out clean, the cake is done.

Cool: Allow the cake to cool in the pan before attempting to remove it. Once cooled, transfer it to a cooling rack to cool even further.

Prepare Blueberry Sauce: In a saucepan, combine the remaining 2 cups of blueberries, dark brown sugar, honey, water, and a dash of lemon juice. Bring the mixture to a boil.

Thicken Sauce: In a small bowl, use 2-3 tablespoons of extra Maizena to create a paste. Gradually add this paste into the boiling blueberry mixture, monitoring the thickness until you achieve the desired consistency.

Simmer and Stir: Reduce the heat to medium and, using a wooden spoon, keep turning the mixture to combine it into a delightful combination of half sauce and half bursting berries.

Pour Over Cake: Carefully pour the blueberry sauce over the cooled cake.

Finish: Sprinkle the top of the cake with a little caster sugar for added sweetness.