01 - Blend the milk and spinach leaves until completely smooth and vibrantly green. Strain through a fine mesh sieve into a medium saucepan to remove any fibrous pieces.
02 - Add heavy cream, sugar, and salt to the saucepan with the green milk. Heat over medium heat, stirring constantly until the mixture steams but never reaches a boil.
03 - Whisk egg yolks in a separate bowl. Slowly pour approximately 1 cup of the hot cream mixture into the yolks while whisking vigorously to prevent curdling.
04 - Return the yolk mixture to the saucepan. Cook over medium-low heat, stirring constantly until the custard thickens enough to coat the back of a spoon, reaching 170-175°F.
05 - Remove from heat immediately. Stir in peppermint and vanilla extracts. Add additional green food coloring drop by drop if a more intense color is desired.
06 - Pour the custard through a fine mesh sieve into a clean bowl. Let cool to room temperature, cover tightly, and refrigerate for at least 4 hours or preferably overnight.
07 - Process the chilled custard in an ice cream maker according to the manufacturer's instructions. During the final 2 minutes of churning, add the dark chocolate chips.
08 - Transfer the churned ice cream to a freezer-safe container with a tight-fitting lid. Freeze for at least 2 hours until firm before serving.