Key Lime Pie Gelato

Combine Key lime zest and 3/4 cup of granulated sugar in a bowl of a food processor. Process until the zest is very fine. Place the zest and sugar in a heavy-bottomed saucepan. Add whole milk and cook on medium heat until the mixture reaches 170ºF on an instant-read thermometer. Remove from the heat, cover with a lid and steep for 30 minutes.

While the milk is steeping, whisk the egg yolks with the remaining 1/4 cup of sugar in a non-reactive medium bowl. Whisk until the eggs are foamy and slightly thickened. Set aside.

Put the steeping milk and zest mixture back on medium heat until it reaches 170ºF, stirring occasionally to prevent scorching. Temper the eggs by pouring in a slow, steady stream of the hot milk while whisking continuously. Once all the hot milk has been added to the egg yolks, pour the new egg and milk mixture (custard) back in the saucepan. Heat on medium, stirring continuously with a wooden spoon or heat proof spatula until it reaches 185ºF or is thick enough to coat the back of the wooden spoon. Take care not to let the mixture boil. If needed, blend or emulsify the custard if it is not smooth.

In a separate clean, large glass or stainless steel bowl, add the heavy cream. Set the bowl over an ice bath and place a fine-mesh sieve over the cream.

Pour the heated custard through the sieve into the cold cream. Stir occasionally until the mixture is fully cooled. Add the lime juice and stir until combined. Remove the bowl from the ice bath and dry the bottom with a kitchen towel. Cover the bowl and refrigerate for at least 8 hours or overnight.

Process the gelato in your ice cream maker according to the manufacturer directions. Remove the gelato from the ice cream maker and gently fold in or layer the crushed graham crackers. Store the gelato in a sealed plastic container. I also lay a piece of plastic wrap on the gelato surface to prevent ice crystals from forming. Freeze until set and ready to serve.

Makes about 1 1/2 quarts.