Preheat your oven to 400℉ and line a baking sheet with parchment paper.
In a medium-sized bowl, add broken pretzels, chopped pecans, cinnamon, and brown sugar, then mix them together. Pour melted butter over ingredients and mix until well combined.
1 cup pretzels, 1 cup pecans, ¼ teaspoon ground cinnamon, ½ cup brown sugar, ½ cup butter
Spread the pretzel mixture on your baking sheet and bake for 8 minutes. Watch them closely, they can burn quickly. Set the pan aside to cool completely, then break it into small pieces.
Fluff
In the bowl of your electric mixer, beat the cream cheese and sugar until smooth. Fold in the Cool Whip and marshmallows until just combined. Cover and refrigerate until ready to serve.