Add the strawberries to a large bowl, and using a pastry cutter or a heavy spoon, mash the strawberries until they are the size of peas. Stir in the sweetened condensed milk. Set it aside.
In the bowl of a stand mixer fitted with the whisk attachment, whisk the cold heavy cream until stiff peaks form, about 2 minutes. (Alternately, use a handheld mixer and beat until stiff peaks form.)
Add half of the whipped cream to the sweetened condensed milk, using a spatula to fold the ingredients together. Fold in the remaining half of the whipped cream then transfer the ice cream to an airtight container with a lid or a metal loaf pan covered securely with plastic wrap and freeze until firm, at least 6 hours.
Notes
If using frozen strawberries, thaw them at room temperature for 10 minutes before mashing.
Add any sort of mix-ins after you’ve folded in all of the whipped cream (fruit, nuts, chocolate chips, etc.) any other extracts (mint, coconut, banana, strawberry, etc.).
To store: Place the container in a sealable plastic bag and ensure plastic wrap (if using) is touching the surface of the ice cream to prevent ice crystals from forming.