Preheat your oven to 350°F (175°C). Prepare six small ramekins by lightly greasing them with cooking spray or butter.
In a mixing bowl, whisk together the eggs and sugar until well combined and slightly frothy.
In a saucepan over medium heat, combine the milk, vanilla extract, and salt. Heat until just warm, but do not let it boil.
Gradually pour the warm milk mixture into the egg mixture while whisking continuously to create a smooth custard base.
If using cornstarch, mix it with a tablespoon of cold water until dissolved, then stir it into the custard mix until well incorporated.
To achieve an ultra-smooth texture, pour the custard mixture through a fine-mesh sieve into another bowl. This will filter out any lumps.
Distribute the custard evenly among the prepared ramekins.
Place the ramekins in a deep baking dish. Fill the dish with hot water until it reaches halfway up the sides of the ramekins.
Carefully place the baking dish in the preheated oven. Bake for 30-35 minutes or until the custard is set but still wobbly in the center.
Remove ramekins from the water bath and allow them to cool for about 10 minutes at room temperature. Then refrigerate for at least 2 hours to fully set.
To serve, run a knife around the edges of the custard to release it from the ramekins. Invert onto a plate and drizzle with caramel sauce. Garnish with fresh berries if desired.