Combine 6 tablespoons sugar and 2 tablespoons cornstarch in a medium saucepan over medium heat. Combine milk and egg, stirring well with a whisk. Gradually add milk mixture to sugar mixture, stirring constantly, and bring to a boil. Cook for 1 minute, stirring constantly. Remove from heat.
Combine pumpkin and the next 4 ingredients (through ground nutmeg) in a bowl, stirring well. Slowly add pumpkin mixture to milk mixture, whisking constantly. Place pan over low heat, and cook for 3 minutes or until thoroughly heated, stirring constantly (do not boil). Divide pudding evenly among 4 dessert bowls, and cover surface of pudding with plastic wrap. Chill.
Line a baking sheet with foil, and coat foil with cooking spray. Place the remaining 2 tablespoons sugar, walnuts, and a dash of salt in a small nonstick skillet; cook over low heat until sugar dissolves and is golden (about 3 minutes), stirring frequently to coat nuts. Transfer mixture to prepared baking sheet, and cool completely. Coarsely chop nuts.
Place cream in a bowl. Beat with a mixer at high speed until stiff peaks form. Top each serving with 2 tablespoons whipped cream and about 1 tablespoon nuts.