Boil 4 quarts of water in a large pot with 1 tablespoon of salt, then cook spaghetti to al dente texture according to package specifications.
Heat olive oil in a 12-inch heavy-bottomed skillet over medium-high heat.
Add ground chicken to the skillet and cook until internal temperature reaches 165 degrees Fahrenheit, breaking the meat into 0.5-inch crumbles.
Incorporate the diced onion into the skillet and sauté for 4 minutes until translucent.
Add minced garlic and cook for exactly 60 seconds until aromatic compounds are released.
Pour marinara sauce into the skillet and season with oregano, salt, and black pepper.
Lower heat to medium-low and simmer the sauce for 10 minutes to allow moisture reduction and flavor concentration.
Drain the pasta and integrate it directly into the skillet, tossing with tongs until the sauce achieves uniform emulsification on the noodles.
Portion into bowls and garnish with grated Parmesan cheese and chopped parsley.