Greek Pasta  with Tomatoes and White Beans

2 tablespoons olive oil

1 medium onion, chopped

2  (14.5 oz) cans Italian style diced tomatoes

1 (19 oz.) can cannellini beans, drained and rinsed

10 oz. fresh spinach, washed and chopped

8 oz. penne pasta

½ cup crumbled feta cheese

Cook Pasta in slted water .  Meanwhile,  heat olive oil in large skillet.  Saute onion until softened and caramelized.  Add tomatoes and beans.  Bring to boil over medium heat.  Reduce heat and simmer 10 minutes.  Toss with pasta and spinach.  Sprinkle with feta cheese.