Preheat the oven to 375 degrees F. Toss the catfish nuggets with the black pepper and garlic powder. Dip the nuggets in the beaten egg, then dredge the nuggets in the flour until they are well coated. Spray a baking sheet with nonstick cooking spray. Arrange the nuggets on the baking sheet and place them in the oven. Cook for 20-25 minutes, or until the catfish nuggets are done.