Heat olive oil over medium heat. Add sliced garlic and red pepper flakes. Cook 60–90 seconds until garlic is golden and oil is red and fragrant.
Add crushed tomatoes carefully. Stir to combine. Add salt, pepper, and oregano.
Reduce to medium-low. Simmer uncovered 18–20 minutes until thick and deep red. Taste and adjust heat with more pepper flakes if desired.
Add pasta water, toss penne directly in pan over low heat 60 seconds. Remove from heat, scatter parsley, finish with pecorino. Serve immediately.
Notes
- Bloom red pepper flakes in oil at the start — this creates complex layered heat not flat spice. - Use 6 garlic cloves minimum — arrabbiata is a garlic-forward sauce by design. - Finish in the pan with pasta water for a glossy, restaurant-quality coating.