In a small saucepan, combine the granulated sugar and water. Place over medium heat, observing carefully as it turns a deep golden color without stirring.

Once the desired color is achieved, carefully pour the caramel into the bottom of a flan mold or small ramekins, swirling to coat the base evenly. Set aside to cool and harden.

In a separate pot, bring the milk to a gentle simmer over low to medium heat.

Gradually whisk in the fine semolina, stirring constantly to ensure there are no lumps.

Add the additional sugar and continue stirring over low heat for about 5 to 7 minutes until the mixture thickens slightly.

Remove the pot from heat and allow to cool for a few minutes to prevent scrambling the eggs.

In a small bowl, beat the eggs with vanilla extract and optional citrus zest until well mixed.

Gradually whisk the egg mixture into the warm semolina mixture, stirring quickly until everything is thoroughly combined.

Pour this mixture into the caramel-lined mold(s).

Place the mold in a larger baking dish filled halfway with hot water (bain-marie style).

Bake in a preheated oven at 160°C (320°F) for 35 to 45 minutes, or until the center is just set but slightly wobbly.

Allow to cool completely, then refrigerate for at least 4 hours; overnight is even better.

To serve, run a knife around the edges and gently invert onto a plate so the caramel drips down the sides, creating an inviting presentation.