Wrap beets with foil, drizzle with olive oil, and roast at 400 for 1 hour or until a fork can easily slip into them.
Meanwhile, wash greens well and finely chop in a food processor. Set aside.
Heat oil in large skillet. Add walnuts and toast, about 3 minutes, stirring frequently. Remove to a bowl.
Add onions and saute until tender and golden brown, about 20 minutes.
Meanwhile, cook pasta according to package directions.
Add chopped beet greens and garlic to onions and cook, stirring frequently, about 3 minutes.
When beets are roasted, remove from foil, remove skin, and cut beets into thin strips. Add beets and greens mixture to pasta. Top each bowl with walnuts and goat cheese.