Preheat oven to 350°F. Mix pumpkin, milk, eggs, sugars, 5 teaspoons of the pumpkin pie spice, vanilla and salt in large bowl until well blended. Pour into 13x9-inch baking pan which has been sprayed with no stick cooking spray.
Mix cake mix and remaining 1 teaspoon pumpkin pie spice in medium bowl with wire whisk. Sprinkle dry cake mix evenly over pumpkin mixture. Sprinkle with pecans. Drizzle evenly with melted butter.
Bake 50 minutes or until golden brown. Serve warm or at room temperature. Serve with whipped cream and Spiced Pecans, if desired. Store leftover dessert in refrigerator.