Prepare the pudding: In a small saucepan, place the yolk (use the white in another meal), butter, sweetener, and a few drops of vanilla flavoring. Pour half of the prepared milk into the saucepan. Add the starch to the rest of the milk. Stir thoroughly until a uniform consistency is achieved (no lumps). Place the saucepan on medium heat. Heat the contents, constantly stirring with a kitchen whisk or fork. It's important to achieve a smooth and uniform consistency. When the saucepan's contents start to gently boil – reduce the heat and begin pouring the milk with starch in a thin stream (stir again just before pouring, so nothing remains at the bottom), constantly stirring at a medium pace with a kitchen whisk or spoon. Keep stirring until all ingredients are combined, then increase the heat to medium. Stir the pudding until it boils and thickens. After a moment, turn off the heat. The pudding should not have any lumps. If lumps appear, try to remove them by stirring more thoroughly and rubbing with the kitchen whisk or spoon.

Transfer the pudding to a bowl. Cover the top of the vessel with plastic wrap (to prevent a skin from forming) and set aside to cool - to speed up the cooling process, you can briefly place it in the freezer.

Transfer the cooled pudding to a blender container. Add softened butter and blend until the ingredients are combined.

Break the biscuits into smaller pieces.

Divide the biscuits and pudding mass into 2 parts. Pour the first layer of biscuits into a small dish. Then lay out a layer of pudding mass. Alternate until all ingredients are used.

Evenly spread coconut flakes on top.

Refrigerate for at least 3 hours, preferably overnight. The pudding mass should thicken, and the biscuits should soften.