Heat oven to 300°F. In 1-quart saucepan, melt butter over medium heat; remove from heat. Stir in brown sugar, pumpkin pie spice, orange peel, vanilla and pepper until well mixed.
In 15x11-inch roasting pan, mix cereal, pretzels and almonds. Pour butter mixture over cereal; toss until evenly coated.
Bake 45 to 60 minutes, stirring every 15 minutes, until golden brown. Cool completely, about 45 minutes. Stir in cranberries and chocolate chunks. Store in tightly covered container.