1 cup heavy cream
1 can (16 ounces/454 g) chocolate syrup
1 teaspoon vanilla
1/2 cup chopped nuts (optional)
Put all the ingredients except the nuts into a bowl; ask an older person to beat them with an eggbeater or a mixer at low speed until frothy and a little thicker.
Stir in the nuts (optional), pour the mixture into a shallow 1-quart (1-liter) casserole, and place in the freezer.
When the mixture is partially set but not yet frozen through (about 45 minutes), pour it back into the bowl and ask the older person to beat it again. (This helps make it smooth.)
Put it back into the freezer until it sets completely (about an hour more).