In a small saucepan, combine the granulated sugar, water, and lemon juice. Place over medium heat and allow the sugar to dissolve without stirring. Continue to cook until the mixture turns a deep amber color, approximately 3-5 minutes. Immediately remove the pan from heat and briefly submerge the base of the saucepan into a bowl of iced water for 10 seconds to halt further cooking. Exercise caution to avoid splashing water into the caramel. Carefully pour or spoon the caramel into the bases of individual ramekins or molds. Set aside to harden.

In a mixing bowl, gently whisk the eggs until well combined. Avoid over-beating to prevent excessive air bubbles. In a separate medium-sized saucepan, combine the full-cream milk, granulated sugar, vanilla extract, and a pinch of salt. Warm the mixture over medium heat, stirring occasionally, until the sugar has completely dissolved and the temperature reaches approximately 158°F (70°C). Remove the saucepan from heat.

Gradually pour the warm milk mixture into the eggs, whisking constantly to combine. For an ultra-smooth texture, strain the mixture twice through a fine-mesh sieve.

Preheat the oven to 300°F (150°C). Pour the custard mixture evenly into the prepared ramekins over the hardened caramel. Tap each ramekin gently on a kitchen towel to release any trapped air bubbles. Cover each ramekin with aluminum foil and pierce a few small holes in each to allow steam to escape.

Line a deep baking tray with a clean tea towel, place the ramekins on top, and add warm water to the tray until it reaches halfway up the sides of the ramekins. Ensure the water is hot but not boiling.

Bake for 35 minutes or until the custard is just set but still has a gentle wobble in the center when lightly shaken.

Remove the ramekins from the water bath and allow them to cool at room temperature for 10 minutes. Once cool enough to handle, discard the foil coverings. Wrap each ramekin tightly with plastic wrap and refrigerate for a minimum of 4 hours, or ideally overnight, to set completely.

When ready to serve, run a thin knife around the inner edge of each ramekin to loosen the custard. Invert the ramekin onto a serving plate and gently lift it off, allowing the caramel to flow over the custard.