In a pot add the milk, the sugar, and transfer over medium heat until it comes to a boil. In a bowl, add the semolina, the cornstarch, and mix. Then add the eggs, vanilla extract, lemon zest, salt, and mix very well with a hand whisk.
With a ladle, slowly add the hot milk from the pot into the bowl with the eggs, by constantly stirring.
Add the mixture into the pot again, transfer on heat, and stir constantly until the cream thickens.
Remove from the heat, add the butter, and mix until it melts.
Butter a 27cm baking dish and sprinkle with semolina. Pour the whole mixture and spread it well with a spatula. Bake in a preheated oven to 180ο C into fan set.
For the coating
In a bowl, add the water, egg, sugar, and mix well.
With a pastry brush, spread it over the whole surface of the milk pie and bake for 40-45 minutes.
Remove from the heat and allow at least 4 hours for it to cool well.
Serve with sugar, honey, cinnamon, and mint.