In a saucepan, combine the milk, semolina, eggs, sugar, and vanilla.

Cook over low heat, stirring constantly, until the custard thickens.

Once thickened, remove from heat and, while still hot, add the butter.

When the butter melts into the custard, stir well to combine.

Add the orange zest if you like.

If the custard gets too thick, thin it with a little water.

Cover with plastic wrap and, while you work with the phyllo, stir the custard occasionally to prevent a skin from forming.

Generously butter the bottom and sides of a baking dish (I use a glass baking dish).

Layer half of the phyllo sheets in the dish, brushing each one well with butter (including the sides).

Spread the custard evenly over the phyllo.

Fold the sides of the bottom phyllo sheets over the custard.

Layer the remaining phyllo sheets on top, brushing each one with butter.

Tuck all the edges of the top phyllo sheets underneath, into the bottom of the dish.

Cut the galaktoboureko into pieces.

Pour melted butter over the top and sprinkle lightly with water.

Bake in a moderate oven at 350°F (180°C) until golden brown.

Simmer the syrup ingredients with the lid on until it starts to foam.

Skim off any foam and pour the hot syrup over the dessert as soon as it comes out of the oven.