Preheat oven to 350 degrees. Line a baking sheet with parchment paper or foil and give it a quick spray of cooking oil spray.
Lay crackers side by side filling the pan.
Melt butter and brown sugar in a sauce pan. Bring to a boil and cook for 3 minutes, stirring constantly.
Slowly pour sauce over crackers, using a large spoon to spread it out and cover all the crackers. Top with chips. Let chips sit for 2 minutes to melt, then carefully spread into an even layer.
Top with nuts, salt and peanut butter cups. Turn oven off and return pan to oven for 5 minutes to melt everything together a bit.
Set aside to chill or refrigerate. Cut or break into pieces. Store in a covered container on the counter or in refrigerator.