01 - Bring a large pot of salted water to a boil. Cook penne pasta according to package directions until al dente. Reserve 1/2 cup pasta cooking water, then drain.
02 - While pasta cooks, heat olive oil in a large skillet over medium heat. Add sliced garlic and sauté for 1 minute until fragrant, avoiding browning.
03 - Stir in crushed red pepper flakes and toast for 30 seconds to release flavor.
04 - Add crushed tomatoes, sea salt, black pepper, and sugar if using. Simmer for 10 to 12 minutes, stirring occasionally, until sauce thickens slightly.
05 - Taste and adjust seasoning as desired. Add additional chili flakes for more heat, if preferred.
06 - Add drained pasta directly to skillet with sauce. Toss gently to coat pasta, incorporating a splash of reserved pasta water for desired sauce consistency.
07 - Remove skillet from heat. Stir in chopped parsley and drizzle lightly with olive oil.
08 - Plate pasta hot, garnishing with freshly grated Parmesan if desired.