Heat oven to 350°F. Lightly spoon flour into measuring cup; level off. In medium bowl, combine flour, 3/4 cup sugar, 2 tablespoons cocoa, 2 teaspoons espresso granules, baking powder, 1/4 teaspoon orange peel and salt; mix well.
Add milk and butter; mix until well blended. Stir in walnuts. Spoon into ungreased 8-inch square (2-quart) baking dish; spread evenly.
In small bowl, combine all pudding ingredients except water; mix well. Sprinkle over batter. Slowly pour hot water over batter.
Bake at 350°F. for 30 to 40 minutes or until edges are bubbly and center is set. Cool at least 10 minutes before serving. Top with whipped cream and additional grated orange peel.