Preheat oven to 350°F (175°C).

In a heavy saucepan over medium heat, melt the sugar until it turns a deep golden brown, stirring constantly.

Quickly pour the caramelized sugar into a 9-inch round cake pan or individual ramekins, tilting to coat the bottom completely.

In a large bowl, whisk together the eggs, sweetened condensed milk, evaporated milk, vanilla extract, and salt until smooth.

Strain the custard mixture through a fine-mesh sieve into the caramel-lined pan.

Place the pan inside a larger baking dish and fill the outer dish with hot water until it reaches halfway up the sides of the custard pan.

Bake for 50 to 60 minutes, or until the center is just set but still slightly jiggly.

Remove from the water bath and let cool to room temperature, then refrigerate for at least 4 hours.

Run a knife around the edges of the pan and invert onto a large rimmed serving plate.