Notice the amount of milk your box calls for. It will be either 2 cups, or 3 cups. Measure out the correct amount and put into medium sized bowl.
Add the contents of the jello pudding box into the same bowl.
Mix the two ingredient at a quick pace for around 2 minutes. You may notice that it becomes tough to mix, push through, it's worth the end result.
Put it in the fridge in individual cups or one big bowl, for at least 5 minutes. Make sure you cover the mousse or else you may find a hard top layer will form. (Although I doubt 5 minutes will create it; but if you have it in there longer you may want to)
ENJOY! (You may find it a bit thick; and if you have some extra 'heavy whipping cream', adding a small amount helps thin it out a little. A little goes a long way when adding more cream.)
Extra Tip: To give it an extreme chocolate flavor add 3-4 Tablespoons of cocoa powder (sifted)when you add the pudding mix into the whipping cream.