Heat olive oil and butter in a skillet over medium heat.
Add diced onion, salt, and pepper. Cook until golden and translucent. Set aside.
Boil ditalini pasta in salted water for 8–10 minutes.
Add peas during the last 2 minutes of cooking.
Drain pasta and peas, then mix with onions.
Stir in parmesan cheese while hot.
Serve immediately with extra cheese and black pepper.
