For Caramel Sauce, put a cup of sugar in a small saucepan, over low heat. Keep your eye on it. If it burns, you will have to start over. it just needs to melt and be slightly golden that's all. Immediately pour the caramel into a metal pan and swirl it around to cover the bottom and sides. You have to be quick because once it starts to cool down you don't stand a chance. The caramel should have cooled down before you pour the pineapple mixture in it.
For Pineapple Mixture, bring juice and 1/2 cup sugar to boil in medium saucepan over high heat, stirring until sugar dissolves. Reduce heat to medium; simmer until mixture is reduced to 2 cups, stirring occasionally, about 25 minutes. Cool to room temperature. Place egg yolks in large bowl. Whisk in pineapple mixture.
Carefully pour into caramelized pan and set the mold in pan filled with hot water. Bake in a moderate oven 350* for about 50 minutes or until golden. Test with a knife, it should come out clean. Remove from oven, cool and refrigate at least 3 hours.