Step 1

Pour the sweetened condensed milk into a large bowl.

Step 2

Mix the vanilla extract, or other flavoring extract, into the condensed milk, if using. (See Recipe Notes for other flavoring ideas.)

Step 3

Whip the heavy cream: Pour the heavy cream into a mixing bowl or the bowl of a stand mixer. Use a hand mixer, stand mixer, or immersion blender to whip the cream until it holds stiff, billowy peaks, about 3 minutes.

Step 4

Lighten the condensed milk: Gently mix a scoop of the whipped cream into the condensed milk. This lightens the condensed milk and makes it easier to fold into the rest of the whipped cream.

Step 5

Fold the whipped cream into the condensed milk: Transfer the rest of the whipped cream to the bowl with the condensed milk. Gently begin folding the whipped cream into the condensed milk. At first, it will look very lumpy. As you continue to fold, the mixture will smooth out and become soft and silky. Stop when you see just a few small lumps here and there — be careful not to deflate the mixture too much or over-mix.

Step 6

Transfer the ice cream base to a freezer container: Use a spatula to scrape all the ice cream base into your freezer container. Smooth the top, then press a piece of wax paper against the surface to prevent ice crystals from forming.

Step 7

Freeze for at least six hours, or up to 2 weeks: The ice cream will become more firm the longer you let it freeze. For best texture and flavor, eat within two weeks.