Make 1 large box of orange flavored jello according to the directions and pour it into a large mixing bowl. Set aside.
Next, make the 1 large box of Jello Brand lemon cooked pudding as directed with the sugar, egg yolks, and water. When it thickens let stand for about 2-3 minutes. Stir it a few times and then pour the lemon pudding into the prepared orange jello in a large bowl. Stir them together until well blended.
Pour the pudding and jello mixture into a 9x13 baking dish or you can do individual servings in mini dessert dishes, shooter cups, or ramekins. Just fill your serving containers 3/4's of the way to the top with the jello/pudding mixuture leaving a little room at the top for the topping and orange.
Put in the refrigerator and chill for at least 6 hours or until it sets up.
Once the jello/pudding mixture has set up and is firm, take it out of the refrigerator. Then in a separate mixing bowl, mix together the 1 cup milk, 1 small box of Jello Brand instant lemon pudding, and 2 cups cool whip. Whisk or stir it together until everything is combined well and it's nice and creamy. Make sure to scrape the bottom of the bowl to ensure it's all mixed well.
Then, spread the Cool Whip mixture evenly on the top of the jello and then top with the 2 small cans of mandarin oranges, drained. If you don't like the oranges, you can leave them off. If you want to do them individually in dessert cups, put a dollop of topping onto each one or, you can use a piping bag or a ziplock bag to pipe the Cool Whip mixture on top. Add a mandarin orange to the top of each one.
Chill until ready to serve.