Preheat the oven to 375°F (190°C) and lightly butter a baking dish or line it with a sheet of Phyllo Pastry for an easier release.
In a medium saucepan combine Whole Milk, Fine Wheat Semolina, Granulated Sugar and a pinch of Salt over medium heat; whisk constantly until the mixture thickens to a very soft pudding.
Beat the Eggs lightly in a bowl. Temper the eggs by whisking a ladle of the hot semolina mixture into the eggs, then pour the warmed egg mixture back into the pan, stirring constantly to avoid scrambling.
Remove the custard from the heat and stir in a knob of Unsalted Butter, Vanilla Extract and the zest (and a little juice if you like) of one Lemon. Cover the surface with plastic wrap to prevent a skin from forming and set aside to cool until just warm.
Brush a sheet of Phyllo Pastry with melted Unsalted Butter and lay it in the prepared dish, repeating to build a sturdy base of several layers (about 4–6 sheets), brushing each sheet with butter.
Pour the warm custard into the phyllo-lined dish and spread evenly. Layer another 4–6 sheets of butter-brushed Phyllo Pastry over the custard, tucking and trimming the edges to seal.
Lightly score the top phyllo into serving-size pieces so it’s easy to cut after baking, brush the surface with a little more melted butter, and transfer to the oven.
Bake until the phyllo is deeply golden and crisp, about 30–40 minutes depending on your oven. Let the bougatsa cool for 10–15 minutes so the custard firms up slightly.
Dust the finished bougatsa with Powdered Sugar and a generous sprinkle of Ground Cinnamon before serving warm. Enjoy slices fresh from the oven.
