In a skillet over medium-high heat, sauté the onion and the garlic in the olive oil. Add the artichoke hearts. Cook to a pale gold color over high heat, then add the tomatoes, seasoning to taste. Simmer 15-20 minutes over medium heat.
Cook the penne rigate until al dente according to package directions in boiling, salted water. Drain and add to the artichoke sauce. Sprinkle with chopped parsley and grated Parmesan.