First, melt the butter and thoroughly grease the baking dish.

Make the syrup by combining the sugar and water in a saucepan. Bring to a boil, then add the vanilla and let it simmer for a bit. If it starts to thicken, add a spoonful of water if needed. Once it reaches a syrupy consistency, add a squeeze of lemon juice, turn off the heat, and set aside to cool.

To prepare the cream: Pour the milk into a saucepan. Dissolve the cornstarch in a little milk, then add it to the saucepan and stir while cold. Place over heat, stirring constantly until it boils. If the cream is too thin, add a little more cornstarch dissolved in milk, a bit at a time. If it gets too thick, add a splash of milk and stir until you get a thick, smooth consistency.