In a skillet, heat oil over medium heat. Add garlic, cook for about a minute then add chili flakes, and cook for a few seconds being careful not to burn.
Stir in the crushed tomatoes, sherry, brown sugar, salt and pepper and let the sauce simmer for 10 minutes. Season with salt to taste.
Cook your penne in salted boiling water. Reserve 1 cup of pasta water and drain the rest. Add 1/4-1/2 cup of the pasta water to your sauce.
Toss the cooked penne in the sauce. If it’s too thick, add more of that reserved pasta water for a silky finish.
Serve hot with a shower of Parmesan, a sprinkle of parsley, and maybe a side of garlic bread if you’re feeling fancy.