Add the heavy whipping cream to the bowl of a stand mixer or to a mixing bowl if using a whisk or hand held electric mixer. Whisk on medium (use the whisk attachment of a stand mixer) until the cream starts to thicken and then increase to hight until soft peaks form. You want fluffy whipped cream that will incorporate easily into the cream cheese mixture, so don't over beat it or it will become too stiff. You can also use about 2 cups of cool whip, but your pie will be sweeter.
If you are using a stand mixer, transfer the whipped cream to a second mixing bowl. No need to clean the bowl of the stand mixer before the next step. If you are using whisk or an electric mixer, get a second mixing bowl that will hold at least 6 cups.
Add the room temperature cream cheese to the mixing bowl or bowl of the stand mixer along with ¼ cup of key lime juice, 10 Tablespoons of powdered sugar, 1 Tablespoon of lime zest, ½ teaspoon of lime oil if using. Use the paddle attachment of a stand mixer or the beaters of an electric hand mixer and mix on low until the liquid has been incorporated, then increase the speed and beat until you have a smooth texture. This can be done by hand with a whisk, but it will take longer.
Gently fold the whipped cream, ½ cup at a time into the cream cheese mixture until it all incorporated. You want to be gentle with this so you don't collapse the whipped cream. See post for video demo if needed.
Once the mixture is uniform in color and smooth, scoop it into the springform pan and smooth the top. Cover and refrigerate for at least 6 hours to chill.
Decorate the top with extra whipped cream and lime slices or serve it as is. Enjoy!