Chocolate Avocado Pistachio Cake with California Avocado Crème Anglaise

1. Preheat oven to 300ºF. Arrange pistachios on a baking sheet and placein oven for about 15 minutes to toast the nuts until they are dry and aromatic. Stir the pistachiosoccasionally, being careful not to allow them to brown; cool completely. Finely grind nuts in the food processor with 1/4 cup sugar and the flour, pulsing on/off, until the consistency of fine meal.
2. Increase oven heat to 350ºF. Butter an 8-inch springform pan, line with parchment paper, then turn paper over.
3. Combine chocolate and butter in a bowl and microwave on medium power for 2 1/2 minutes Stir until smooth.
4. Beat egg yolks with the whisk attachment in the bowl of an electric mixer on medium speed. Gradually add 1/2 cup sugar and continue beating until yolks are very thick. Add the avocados to the mixer, increase speed, and beat until smooth. Reduce speed to low and gradually stir in the vanilla and chocolate and nut mixtures.
5. In a medium bowl, beat the egg whites with cream of tartar on medium speed until soft peaks form. Add 1/4 cup sugar, 1 Tbsp. at a time, and continue beating until stiff, but not dry. Gently fold the beaten whites into the yolk mixture (yolk mixture will be very thick).  Fold the yolk mixture back into the remaining whites.  Pour into the prepared pan. Tap the pan on the work surface and smooth top with a spatula to level. Bake about 40 minutes or until a toothpick inserted into the center comes out almost clean. Allow the cake to cool in pan.
6. Remove sides of the springform pan and using a long spatula, slide the cake off the paper onto the serving plate. Sprinkle with powdered sugar. Ladle Crème Anglaise into the center of each dessert plate, place a wedge of cake in the center of the plate and serve immediately.

California Avocado Crème Anglaise
Do-Ahead:  The sauce can be completely prepared a day or so before serving.

Instructions

1. Place the avocado in afood processor,   pulsing on/off, until coarsely chopped.
2. Mix milk and sugar together in a small heavy saucepan and bring just to a boil over medium heat.
3. Whisk egg yolks together just to blend in a medium bowl.
4. Whisk scalded milk into the yolks, a drop at a time, and return the mixture to the saucepan. Stir over medium-low heat with a spatula until the sauce thickens. Do not allow the mixture to simmer or boil at anytime or it will curdle. Add the mixtureto the avocado in the food processor and process, stopping to scrape down the sides of the container, until completely puréed. Cover and refrigerate until 30 minutes before serving.