In a medium saucepan, combine the heavy cream, milk, agave syrup and vanilla. Place the saucepan over low heat. Bring the mixture to a simmer. Be sure to whisk often. Remove from the heat and set aside. 

In a medium heatproof mixing bowl, combine the egg yolks and sugar. Whisk vigorously until the mixture is pale yellow and frothy. Pouring in a slow steady stream, gradually whisk the hot cream mixture with the egg mixture.

Return the mixture to the saucepan and, once again, place it over low heat. Stir constantly with a wooden spoon, until a thick custard forms for about 5 minutes.

You can test to see if it's ready by drawing a finger across the back of the spoon. If it leaves a trail, your custard is ready.

Remove the custard from the heat and transfer the mixture into a clean mixing bowl. Place in the refrigerator and allow to chill for at least 2 hours. 

Once the custard has chilled, remove it from the refrigerator and process the custard in an ice cream maker according to the manufacturer's instructions.

When the consistency of the ice cream is similar to soft-serve, melt the chocolate with the salt. Add the optional coconut oil and pour very slowly into the ice cream while it's churning. A slow and steady stream will produce the best results.

You can do this by pouring from a spouted glass measuring cup. Or transfer the melted chocolate into a quart-size plastic bag and make a small cut on one corner. When the melted chocolate hits the cold ice cream it will immediately solidify into small pieces.

Continue churning the ice cream until it's more solid, about 10 to 15 minutes more depending on your machine. Place the ice cream into a freezer-friendly container. Cover and freeze for at least 3 to 4 hours.