In a large pot, heat the olive oil over medium heat. Add the minced garlic and sauté for about 10 seconds until fragrant. Add the chopped cayenne pepper and chili flakes. Cook until garlic turns light golden, about 1 minute.

Pour in the canned crushed tomatoes, kosher salt, and black pepper. Rinse the empty tomato can with a splash of water and add it to the pot. Increase heat to high and stir until the sauce simmers. Reduce to medium and let simmer for 15 minutes, tasting and adding sugar if too acidic.

In a separate large pot, bring salted water to a boil. Add penne and cook according to package directions until al dente, about 11-12 minutes. Reserve 1 cup of the pasta cooking water before draining.

Add the drained penne into the pot with the sauce. Pour in 1/2 cup of reserved pasta cooking water, tossing until the pasta is well-coated. Add more reserved water if needed to reach desired consistency.

Divide the pasta into bowls and garnish with grated Parmesan and parsley if desired. Serve immediately.