In a large heavy saucepan, stir the sugar and cornstarch together. Stir in the cream and milk and cook over medium heat, stirring constantly for about 10 minutes, or until the mixture thickens and begins to bubble.
Add the mint sprigs. Set the pan into a bowl of ice water to cool the mixture down quickly and stir occasionally until cool; discard the mint after 5 minutes. If you leave the mint in too long the flavor will be too strong. Cover the mint cream and refrigerate about 4 hours, or until completely cold.
Freeze the mint cream in an ice cream maker according to the manufacturer's instructions until frozen.
While the milk mixture is cooling, melt the chocolate. I did it in the microwave but can also done in an double boiler. Cool until the chocolate is barely warm and still fluid.
After the gelato is processed, working quickly, drizzle the melted chocolate into the gelato while whisking or stirring vigorously. The chocolate will flake apart as it hits the cold gelato, forming bits of chocolate throughout, stir with a wooden spoon..
Serve immediately, or transfer to a container and freeze until firm, 3 to 4 hours.
Read more at: http://www.foodnetwork.com/recipes/fresh-mint-chip-gelato.html?oc=linkback
recipe makes 1 qtStored in an airtight, insulated ice cream container it will last for a couple of weeks.Substitute fresh mint with 1 tsp mint extract.