Heat the olive oil in a large saucepan over medium heat.
Add the sliced garlic and crushed red pepper flakes and cook, stirring frequently, for 1–2 minutes until the garlic is fragrant and beginning to soften.
Stir in the tomato paste and cook briefly to combine.
Add the crushed tomatoes, salt, black pepper, and sugar, then bring the sauce to a steady simmer.
Reduce heat to medium-low and simmer the sauce for about 15 minutes, stirring occasionally.
While the sauce simmers, bring a large pot of salted water to a rolling boil and cook the penne for 8–9 minutes until al dente, then drain well.
Add the drained pasta to the sauce and toss to coat evenly.
Stir in the chopped fresh basil, mix well, and adjust seasoning if needed.
Serve warm with plenty of grated Parmesan cheese on top.
