In a large pot, bring water to a boil and cook off thin spaghetti. Preheat oven to 200 degrees F.
While the water is boiling, cook diced onions and garlic in 1 T extra virgin olive oil until onions are translucent. Add in the marinara, basil, and seasonings and bring to a light boil.
Slice the top third of the tomato, reserving the top for garnish as a "top hat." Scoop the insides of the tomato out and add into the marinara sauce that is by now boiling.
Once pasta is cooked and drained, lightly toss pasta with marinara. Swirl with fork and gently place portioned pasta into tomato shells. Put tomatoes in a glass casserole dish that will hold up your tomatoes and cook in oven for 10-15 minutes. Top with additional sauce and top with Parmesan if desired. Serve with tops on and enjoy!