Preheat your oven to 350°F (175°C).
In a saucepan, melt 1 cup of sugar over medium heat, stirring until it turns golden brown.
Quickly pour the caramel into a round baking dish, tilting to coat the bottom.
In a blender, combine eggs, sweetened condensed milk, evaporated milk, vanilla extract, and salt.
Blend until smooth, then pour the mixture over the caramel in the baking dish.
Place the baking dish in a larger baking pan filled with hot water.
Bake in the preheated oven for about 50 minutes or until set.
Remove from the oven and let it cool at room temperature.
Refrigerate for at least 4 hours or overnight to set completely.
To serve, run a knife around the edges and invert onto a plate to release the flan.