1. In a bowl, whisk the mayonnaise with the egg, mustard, Old Bay, paprika and scallions. Fold in the crabmeat and 1/2 cup of the pretzels. Refrigerate the crab mixture for 1 hour, until the pretzels are moist.
2. Preheat the oven to 400°. Form the crab mixture into eight 2 1/2-inch patties. Coat the crab cakes with the remaining 1/4 cup of ground pretzels. In an ovenproof nonstick skillet, melt the butter in the oil. Add the crab cakes and cook over moderately high heat until browned on the bottom, about 3 minutes. Turn the crab cakes and transfer the skillet to the oven. Bake the crab cakes for about 5 minutes, until they are browned all over, then serve.