In a large saucepan cook sweet potatoes and turnips in enough boiling water to cover for 15 to 20 minutes or just until tender. Drain and set aside until cool enough to handle.
Preheat oven to 375 degrees F. Meanwhile, trim fat from pork chops. In a small bowl combine 1/4 teaspoon of the salt, the paprika, cumin, and cinnamon. Sprinkle evenly over the pork chops. Coat a large nonstick skillet with cooking spray. Heat over medium-high heat. Add pork chops to skillet. Cook for 3 to 4 minutes or until browned but not fully cooked, turning to brown both sides evenly. Remove from skillet and set aside.
Add oil to the same skillet. Add onion and cook for 3 to 5 minutes or just until tender, stirring occasionally. Stir in garlic. In a medium bowl whisk together milk and flour until smooth. Add all at once to onion mixture along with remaining 1/4 teaspoon salt and the black pepper. Cook and stir until thickened and bubbly. Remove from heat.
Thinly slice turnips and arrange in a 3-quart rectangular baking dish. Pour half of the sauce over turnips. Arrange pork chops in a single layer over turnips. Thinly slice sweet potatoes and place around and in between chops. Pour remaining sauce over potatoes. Sprinkle with panko.
Bake, uncovered, for 25 to 30 minutes or until heated through and pork chops are cooked through. Let stand for 10 minutes before serving. If desired, sprinkle with parsley.