Heat oven to 350° F. Place eight 4-ounce ramekins or one 8- or 9-inch cake pan inside a roasting pan and set aside.
Cook the sugar and ¼ cup water in a small saucepan over medium heat, stirring, until the sugar dissolves and the mixture comes to a boil. Stop stirring and continue to boil the mixture. When it begins to turn brown, swirl the pan continuously until the mixture is amber in color. (Do not stir; this will cause the sugar to crystallize.) Immediately pour the caramel into the ramekins or cake pan; set aside to harden.
In a large bowl, whisk together the eggs, egg yolks, condensed milk, cream, pineapple juice, vanilla, and salt until smooth. Divide the egg mixture among the ramekins.
To the roasting pan, add just enough hot water to reach halfway up the sides of the ramekins or cake pan. Cover the roasting pan with foil and transfer carefully to oven. Bake until the edges of the flan are set but the center is still wobbly, 60 to 65 minutes for ramekins or 70 to 75 minutes for a cake pan. Remove the foil.
Let the flan cool in the water for 30 minutes, then remove and refrigerate until cool, at least 4 hours and up to 3 days. Before serving, run a knife around the edges of the flan and invert onto plates.