Heat oven to 350 degrees (325 degrees for a dark or nonstick pan). Spray botton and sides of a 13X9 inch baking pan with non-stick cooking spray. In medium bowl, beat pumpkin , evaporated milk, eggs, sugar and 4 teaspoons of pumpkin pie spice with wire whisk until smooth. Pour into pan.
Sprinkle dry cake mix over pumpkin mixture. Sprinkle with pecans. Pour melted butter evenly over top.
Bake 50 to 60 minutes or until knife inserted in center comes out clean. Cool 30 minutes.
Serve warm or chilled with whipped topping. Store covered in refrigerator.