Preheat the oven to 175 degrees C. In a saucepan over medium heat, melt the sugar until golden. Gently pour the hot syrup into a round glass baking dish, set aside.
Beat the eggs in a large bowl. Add sugar-free condensed milk and mix the vanilla until smooth. Pour the egg mixture into the baking dish. Cover with aluminum foil. Bake in a preheated oven for 60 minutes. Let's cool completely.