Add the heavy cream to the bowl of a stand mixer fitted with the whisk attachment. Beat on medium-high speed until stiff peaks form, about 3 minutes.

Transfer the whipped cream to a separate bowl and set aside until ready to use.

Remove the whisk attachment from the mixer and add the paddle attachment. To the original mixer bowl (no need to clean it), add the cream cheese and sour cream (if using).

Mix on medium speed until it is smooth and well combined-- about 1 minute.

Next, turn the mixer to low and slowly add the powdered sugar.

Once all of the sugar has been incorporated, add the vanilla and turn the mixer to medium speed. Beat on medium speed until the mixture is light and smooth-- about 2 minutes.

Add the whipped cream back to the bowl and use a rubber spatula to gently fold it into the cream cheese mixture.

Once the mousse is fully combined, transfer it to your choice of serving dish and store it in the fridge for at least 2 hours before serving.

Store any leftovers in an airtight container in the fridge for up to two days.