In a large pan, saute the chopped garlic in olive oil for 1 minute while cooking the pasta in a separate pot. Add spinach to pan and saute for another minute. Then add the can of diced tomatoes and the tomato sauce. Continue cooking this on low heat while the pasta cooks (separately). Drain pasta and add to tomato, spinach and garlic mixture. Drop ricotta cheese by spoonful on top, then sprinkle with parmesan cheese and bake at 350 degrees for 25 minutes.