In a large skillet, melt 1 tablespoon butter over low heat. Add shallots, and cook until translucent, about 5 minutes. Add leeks and champagne; season with salt and pepper. Cook until leeks are tender, 10 to 15 minutes.
In a large nonstick skillet, heat oil and remaining 1/2 tablespoon butter over medium heat. Season scallops with salt and pepper. Add scallops to skillet in a single layer, and cook until just golden brown on both sides. Remove scallops; set aside. Divide leek mixture between 4 plates. Top with scallops, and sprinkle with parsley. Serve immediately.