In a large skillet or pot, add olive oil, onions, and garlic and saute over medium heat for 2 minutes. Add chopped bell peppers, and saute for 2-3 more minutes. Sprinkle red pepper flakes, oregano, salt and pepper over the vegetables, stir.
Add the entire jar of Barilla® Marinara sauce, water, and Barilla® organic penne; stir to combine. Bring the liquid up to a boil, reduce heat to a simmer, then cover. Cook for 12-15 minutes, or until al dente, stirring occasionally throughout.
Preheat broiler on high.
Add baby spinach leaves, cover and let steam for 1 minutes, then stir into the pasta.
Sprinkle cheese over the top of the pasta, place under the broiler and cook for 1-2 minutes, or until cheese is melted, browning and bubbly. Remove, sprinkle top with chopped parsley.