1. Drain beets, reserving liquid. Cut beets into julienne strips, and place in a bowl.
2. Heat olive oil in a saucepan over medium heat. Add shallots; sauté 2 minutes or until tender. Stir in reserved beet juice and vinegar. Bring to a boil, and cook 12 minutes or until syrupy; pour over beets. Toss well. Set aside.
3. Preheat oven to 425°.
4. Spread each baguette slice with 1 teaspoon goat cheese, and sprinkle with 1 teaspoon walnuts. Arrange slices in a single layer on a baking sheet coated with cooking spray. Coat slices with cooking spray.
5. Bake at 425° for 5 minutes.
6. Arrange 1 cup watercress on each of 6 plates. Spoon about 1/2 cup beet mixture evenly over each serving. Top each serving with 2 toast slices.