Instructions

1. 1

   Heat milk and sugar over medium heat in a medium saucepan until just comes to a boil, stirring occasionally. Stir in the vanilla.

2. 2

   Have ready a large bowl filled with ice and set a small metal bowl over the ice with a strainer set over it.

3. 3

   Place egg yolks in a medium bowl, lightly beaten. Ladle some of the milk into the egg yolk, whisk it to prevent curdling.

4. 4

   Pour this mixture back into the rest of the milk in the saucepan. Cook over low-medium heat until mixture is thick and can cover the back of a wooden spoon, about 4 to 8 minutes.

5. 5

   Pour the mixture over the strainer into the small bowl; stir in the yogurt.

6. 6

   Whisk the mixture over the ice bath until it cools completely.

7. 7

   Scoop the avocado meat and puree in a blender or food processor along with the lemon juice and some of the cooled custard.

8. 8

   Pour this mixture back to the rest of the custard, blend them together until it is thick and creamy.

9. 9

   Freeze the custard in an ice cream maker according to the manufacturers instructions. Halfway through the freezing process, fold in the chopped bittersweet chocolate.

10. 10

    Transfer the frozen yogurt into a freezer-safe container and freeze until solid, at least 4 hours.