Heat olive oil in a large, deep skillet or pot over medium heat. Add the sliced garlic and red pepper flakes, cooking for about 1-2 minutes until the garlic is fragrant and just starting to turn golden (watch it carefully!).
Pour in the crushed tomatoes and vegetable broth. Add oregano, salt, pepper, and sugar if using. Stir everything together and bring to a boil.
Add the penne pasta directly to the sauce, making sure it's mostly submerged. Give it a good stir.
Reduce heat to medium-low and let simmer for 12-15 minutes, stirring every few minutes to prevent sticking. The pasta should be tender and most of the liquid absorbed.
If the sauce gets too thick before the pasta is done, add a splash of water or broth. If it's too thin, let it cook uncovered for a few extra minutes.
Remove from heat and stir in fresh basil. Taste and adjust seasonings—add more salt or red pepper flakes if needed.
Serve immediately with plenty of grated Parmesan cheese on top. A drizzle of good olive oil doesn't hurt either!