Dairy

Serve this sherbet with Almond Meringue Wafers (recipe follows).

Bosc pears must be very ripe; Anjou, which are juicier, can be slightly firm. Avoid enamel baking dishes, as they cause the syrup to burn.

For the creamiest results, allow the mascarpone to stand at room temperature for 15 minutes before serving.

Use small red or white potatoes if fingerling potatoes are unavailable.

Chihuahua, Cotija, and Mexican crema give the dish authentic flavor, but Monterey Jack, French feta, and sour cream are good substitutes.

For a less formal but equally appealing presentation, you can spoon rather than pipe the filling into the shells.

You can make the polenta through step 1 ahead of time; let cool, then cover and refrigerate.

This recipe can be made a day ahead and refrigerated; reheat before serving.