Preheat oven to 350 degrees F (325 if using a glass pan).
Pulse graham crackers and pretzels in a food processor or blender until finely ground. (Or place them in a resealable plastic bag and mash with a spoon. Place in a large mixing bowl and stir with melted butter to combine.
Spray the bottom and sides of a 9"x9" pan with cooking spray or grease with butter. Press graham cracker mixture in an even layer along the bottom of the pan. Top with sweetened condensed milk, then cover with coconut flakes, chocolate chips and butterscotch chips. Finish with a sprinkling of mini Cadbury eggs.
Bake for 25 to 30 minutes, or until the coconut flakes and sweetened condensed milk have turned lightly golden in spots. Let cool completely—at least 20 minutes—before removing from pan, slicing and serving.