Preheat oven to 350 degrees F. Grease a 13x9 inch pan.
In a large bowl combine pumpkin, milk, pumpkin pie spice, sugar, eggs and cinnamon. Mix until well combined. Pour batter into prepared pan.
Sprinkle cake mix, and chopped pecans if using, evenly over the top pumpkin mixture. Slice butter into thin pats and cover entire surface of cake with thin pats of butter.
Bake for 60 minutes. Serve warm or cold, with ice cream or whipped cream.
Calories: 247kcal | Carbohydrates: 21g | Protein: 5g | Fat: 17g | Saturated Fat: 8g | Cholesterol: 78mg | Sodium: 127mg | Potassium: 243mg | Fiber: 2g | Sugar: 17g | Vitamin A: 8678IU | Vitamin C: 3mg | Calcium: 106mg | Iron: 1mg