• Preheat oven to 325 degrees F. Grease the bottom of a 9x13 inch glass baking dish.
• In a mixing bowl, combine the cake mix, pudding mix, eggs, oil and water.
• Beat the mixture on low until blended, the increase mixer speed and beat on medium for about 2 minutes or until smooth.
• Pour batter into the pan and bake for about 40 minutes or until cake springs back when touched.
• Set the cake on a rack to cool.
• Put butter in a large (3 quart) nonstick saucepan and begin melting over medium heat.

Pineapple Topping

• When butter is about halfway melted, add evaporated milk and sugar. Continue cooking over medium heat, whisking often, until butter is completely melted and mixture is hot and just beginning to simmer around the edges.
• Whisk ⅓ cup of the hot milk mixture into the egg yolks to temper, then whisk egg yolk mixture into saucepan and continue cooking over medium, whisking constantly, until mixture boils and thickens.
• Whisking constantly, cook at a gentle boil for a little over a minute. Mixture will thicken slightly, but will not be as thick as pudding.
• Remove from heat and let cool for about 5 minutes. Add vanilla extract and drained pineapple and leave mixture to cool at room temperature. It will still be slightly loose at this point, but will thicken a bit more when refrigerated.
• When cake is cool, pour pineapple mixture over cake. Place in refrigerator and chill until pineapple topping sets.