We prefer the flavor of 70 percent dark chocolate in this recipe, though higher cacao percentages will also work.
Combine water, sugar, cocoa, vanilla, espresso powder (if using), and salt in small saucepan. Bring to simmer over medium heat and cook, stirring occasionally, until sugar and cocoa dissolve, about 2 minutes. Remove saucepan from heat and cover to keep warm.
Scoop flesh of avocados into food processor bowl and process until smooth, about 2 minutes, scraping down sides of bowl as needed. With processor running, slowly add warm cocoa mixture in steady stream until completely incorporated and mixture is smooth and glossy, about 2 minutes.
Microwave chocolate in bowl at 50 percent power, stirring occasionally, until melted, 2 to 4 minutes. Add to avocado mixture and process until well incorporated, about 1 minute. Transfer pudding to bowl, cover, and refrigerate until chilled and set, at least 2 hours or up to 24 hours. Serve.
