Heat oven to 350 degrees F. Spray 13x9 inch glass baking dish with cooking spray.
Place pretzels in resealable food-storage plastic bag; smash with rolling pin or flat side of meat mallet until crushed. In medium bowl, mix crushed pretzels, brown sugar and pumpkin pie spice. Stir in butter. Press mixture onto bottom of baking dish. Bake 9-11 minutes or until set. Cool on colling rack.
Meanwhile, in large heatproof bowl, pour boiling water on gelatin; stir until gelatin is dissolved. Add enough cold water to reserved juice to equal 2 cups; stir into gelatin. Refrigerate until partially set, about 1-2 hours.
In medium bowl, beat cream cheese and granulated sugar with electric mixer on medium speed until light and fluffy. Fold in whipped topping. Spread mixture evenly over cooled pretzel crust.
Finely shop mandarin orange segments (I left mine whole); gently stir into partially set gelatin. Carefully pour over cream cheese layer. Refrigerate 8 hours or overnight. Cut into squares.
Calories per serving without ingredient adjustment is 300 calories.
Just imagine how much lower it could be if you changed your ingredients to low-fat, sugar-free, and low calorie.