In a large pot, bring salted water to a boil. Add the penne pasta and cook according to package instructions until al dente. Drain and set aside, reserving about 1 cup of pasta water.
In a large skillet, heat the olive oil over medium heat. Add the minced garlic and chopped red chilies. Sauté for about 1-2 minutes until the garlic is fragrant but not browned.
Pour in the diced tomatoes with their juice. Stir to combine, and bring the mixture to a simmer.
Add sugar, salt, and pepper to taste. Let the sauce simmer for about 10-15 minutes, stirring occasionally until it thickens slightly. If the sauce gets too thick, add a little reserved pasta water to reach your desired consistency.
Add the cooked penne to the skillet with the sauce. Toss gently to coat the pasta evenly. If needed, add more reserved pasta water to help the sauce adhere.
Once combined, remove from heat and garnish with fresh basil leaves. Serve hot with grated Parmesan cheese if desired.
Notes
Adjust the number of chilies based on your spice preference.