Directions

1. 1

   In a heavy-bottomed saucepan, combine the whole milk, heavy cream, granulated sugar, corn syrup, and salt. Place over medium heat and stir frequently until the sugar dissolves completely and steam just begins to rise from the surface. Remove from heat, then add the vanilla bean seeds and the split vanilla pod itself. Cover the pan and allow the mixture to steep for 30 minutes to infuse the vanilla flavor.

2. 2

   While steeping, pour the egg yolks into a separate small bowl and whisk them together gently until slightly lightened in color. After 30 minutes, return the milk mixture to medium heat until light steam appears again. Begin tempering the egg yolks by slowly whisking in about 1/4 cup of the warm milk mixture at a time, pausing between additions to ensure the yolks warm gradually. Continue this process until roughly half of the milk mixture has been incorporated and the yolk mixture feels warm to the touch. This gradual tempering prevents the eggs from scrambling.

3. 3

   Pour the tempered yolk mixture back into the saucepan with the remaining milk mixture and return to medium heat. Stir constantly with a wooden spoon or heatproof spatula for 5 to 7 minutes, until the custard thickens slightly and coats the back of the spatula. Use an instant-read thermometer to confirm the mixture reaches 165 to 170°F. Do not allow the mixture to boil. Remove from heat immediately.

4. 4

   Pour the hot custard through a fine mesh sieve into a clean bowl, discarding the vanilla pod and any cooked egg bits. Set up an ice bath by placing the bowl in a larger bowl filled with ice and water (or use a sealed zip-top bag submerged in ice water). Stir the custard occasionally as it cools to room temperature. Once cooled, cover and refrigerate for at least 3 hours, preferably overnight, until completely chilled. Churn the gelato according to your ice cream maker's manufacturer instructions.

5. 5

   While the gelato is churning, combine the finely chopped dark chocolate and unsalted butter in a small saucepan and melt together over low heat, stirring gently until smooth. Alternatively, melt them together in the microwave in 15-second intervals, stirring between each burst. Pour the melted chocolate mixture into a zip-top bag, seal it well while pressing out as much air as possible, and keep it in a warm water bath if needed to maintain pourable consistency.

6. 6

   When the churning gelato reaches the consistency of soft-serve ice cream—about 1 to 2 minutes before the churning cycle completes—snip a 1/4 inch opening at one corner of the zip-top bag containing the melted chocolate. Slowly drizzle most of the chocolate in a thin stream into the churning gelato, allowing the chocolate to break apart and create thin ribbons throughout.

7. 7

   Transfer the gelato to a freezer-safe container, drizzling the remaining melted chocolate across the top in a thin stream. Freeze for 2 to 3 hours, or overnight, until the gelato is completely firm and ready to serve.