Preheat oven to 250°F. Blend pretzels, cereal, and nuts in large bowl. Set aside.
Spray a large shallow roasting pan with cooking spray. Mix brown sugar, corn syrup, butter and salt in a heavy 2-quart saucepan. Stirring constantly, bring to a boil over medium heat. Boil 5 minutes without stirring. Remove from heat. Stir in baking soda and vanilla.
Pour syrup mixture over pretzel mixture, stirring to coat evenly. Pour into baking pan. Bake for 45 minutes, stirring occasionally. Remove from oven and thinly spread on foil that has been sprayed with cooking spray.
Cool; break apart. Toss with peanut butter candies. Store in tightly covered container.
Variations: Sweet and Tart: Substitute 1/2 cup filled red licorice pieces and 1/2 cup miniature sweet and sour candy pieces for the candy corn and peanut butter pieces. Rainbow Chocolate: Substitute 1 cup candy coated chocolate pieces for the candy corn and peanut butter pieces.