Heat olive oil in a large skillet over medium-high heat. Add the Italian sausage and cook, breaking it up with a spoon, until browned. Drain off any excess grease.
Add the chopped onion to the skillet and cook until softened, about 5 minutes. Stir in the minced garlic and cook for another minute until fragrant.
Pour in the diced tomatoes (undrained) and chicken broth. Bring to a simmer.
Add the gnocchi to the skillet. Stir gently to combine. Cover and simmer for 10-12 minutes, or until the gnocchi are cooked through and tender.
Stir in the heavy cream and grated Parmesan cheese. Cook for another 2-3 minutes, stirring constantly, until the sauce has thickened and is creamy.
Season with salt and pepper to taste. Stir in the fresh chopped basil just before serving.
Notes
Serve hot, garnished with extra Parmesan cheese if desired. This dish is best enjoyed immediately.