Avocado Brownies

• 4 oz mashed avocado (about ½ c)
• 4 oz sugar
• 4 T unsalted butter, melted
• 1 egg
• vanilla
• ½ t salt
• ½ t espresso powder
• 60 g Dutch process cocoa
• 1 oz WWW flour
• ½ c bittersweet chocolate chips
• ½ c walnuts

8″x8″ pan, greased. 350º 35 mins.