1 1/2 cups heavy cream
Grated zest from 2 limes
6 large egg yolks
1 (14- or 15-ounce) can sweetened condensed milk
1/2 cup Key lime juice (bottled or use fresh squeezed from regular or Key limes)
Bring the cream and zest to a simmer in a heavy medium saucepan. Slowly beat the hot cream into the egg yolks in a medium mixing bowl. Pour the entire mixture back into the pan and place over low heat. Stir constantly with a whisk or wooden spoon until the custard thickens slightly. Be careful not to let the mixture boil, or the eggs will scramble. Remove from the heat and pour the hot custard through a strainer into a large, clean bowl. Allow the custard to cool slightly, then stir in the sweetened condensed milk and lime juice. Cover and refrigerate until cold or overnight.
Stir the cold custard well, then freeze in 1 or 2 batches in your ice cream machine according to the manufacturer’s instructions. When finished, the ice cream will be soft but ready to eat. For firmer ice cream, transfer to a freezer-safe container and freeze at least 2 hours. Makes about 1 quart or 8 servings.
Per serving (per 1/2 cup): 363 calories; 25 g fat (14 g saturated fat; 62 percent calories from fat); 30 g carbohydrates; 238 mg cholesterol; 85 mg sodium; 7 g protein; 0.1 g fiber.