Sauté the meat
Set the Instant Pot to Sauté mode. Add olive oil, then ground beef and diced onion. Cook for 4–5 minutes, breaking up the meat until browned. Drain excess grease if needed.
Add garlic and seasoning
Stir in minced garlic, salt, pepper, Italian seasoning, and paprika. Cook 30 seconds until fragrant.
Layer the ingredients
Pour in marinara sauce and water (or broth). Stir gently to combine.
Add spaghetti (do not stir)
Break spaghetti in half and lay it in a crisscross pattern over the sauce. Gently press the noodles down so they are mostly submerged, but do not stir.
Pressure cook
Secure lid and set valve to sealing. Cook on High Pressure for 8 minutes.
Quick release
Once done, carefully perform a quick release. Open lid and stir everything together. The sauce will thicken as it sits.
Finish & serve
Let rest for 2–3 minutes. Serve warm topped with Parmesan cheese and fresh herbs.