Silky vanilla custard with a golden caramel top is a timeless Mexican dessert. This family-favorite treat is a smooth, elegant, comforting classic for any occasion.
Preheat oven to 325°F. Place a rack in the middle position and bring a kettle of water to boil for the water bath.
In a small saucepan over medium heat, melt 0.75 cup sugar, swirling gently until it turns a deep golden caramel. Immediately pour the caramel into a 9-inch round baking dish, tilting to coat the bottom evenly.
In a mixing bowl, whisk whole eggs and yolks together until smooth but not frothy. In a separate bowl, combine whole milk, sweetened condensed milk, vanilla extract, and salt.
Slowly stream the milk mixture into the eggs while whisking gently to avoid air bubbles, ensuring a silky custard base.
Pour the custard mixture over the cooled caramel in the baking dish. Place the dish in a large roasting pan and fill the pan with hot water until it reaches halfway up the sides of the baking dish.
Bake flan in the water bath for about 60 minutes, or until the center is just set but still slightly wobbly. Remove carefully and let cool to room temperature, then chill at least 4 hours in the refrigerator.
To serve, run a thin knife around the edge of the flan. Invert onto a large plate so the caramel tops the custard. Slice and serve cold.