Cut the avocados in halves, remove the pits and scoop out the flesh. Place the avocado, lemon juice and condensed milk in a food processor and process until smooth. Set aside.
In a large bowl, beat the cream until stiff peaks form. Add the avocado mixture and fold it in until no white streaks can be seen.
Spoon the mixture into a container, preferably a glass one with a lid. Cover the entire top surface with a plastic wrap and then cover with the lid. Freeze for at least 8 hours or overnight.