Cut a lengthwise slit down the center of the tenderloin to within 1/2 in. of bottom. Open tenderloin so it lies flat. On each half, make another, lengthwise slit down the center to within 1/2 in. of bottom; cover with plastic wrap. Flatten to 1/4-in. thickness. Remove plastic wrap; sprinkle pork with 1/4 teaspoon celery salt, 1/4 teaspoon garlic powder and 1/4 teaspoon pepper. Layer with the cheese, spinach and ham. Press down gently., Roll up jelly-roll style, starting with a long side. Tie the roast at 1-1/2-inch to 2-inch intervals with kitchen string. Sprinkle with remaining celery salt, garlic powder and pepper. Place on a rack in a shallow baking pan., Bake, uncovered, at 425° for 25-30 minutes or until a thermometer reads 160°. Transfer to a serving platter. Let stand for 10 minutes before slicing.