Penne all’Arrabbiata Recipe (Spicy Tomato Pasta)

Ingredients

• 1 pound uncooked penne pasta
• 2 tablespoons olive oil
• 1/2 cup finely chopped onion
• 3 garlic cloves, minced
• 1 to 1-1/2 teaspoons crushed red pepper flakes
• 3 tablespoons tomato paste
• 1 can (28 ounces) crushed tomatoes
• 1 teaspoon salt
• 1 teaspoon sugar
• 1/4 teaspoon pepper
• 1/4 cup grated Parmesan cheese
• Chopped fresh parsley, optional