Heat the olive oil in a large deep skillet or pot over medium heat.
Add the Italian sausage, breaking it up with a spoon, and cook until browned and cooked through, about 5-7 minutes.
Add the chopped onion and cook until softened, about 3 minutes.
Stir in the minced garlic and cook for 1 minute until fragrant.
Pour in the chicken broth and heavy cream, then add the dried Italian seasoning. Stir to combine and bring the mixture to a simmer.
Add the potato gnocchi to the pot, stirring gently to submerge them in the liquid.
Simmer uncovered, stirring occasionally, until the gnocchi float to the surface and the sauce thickens slightly, about 5-7 minutes.
Stir in the grated Parmesan cheese until melted and the sauce is creamy.
Add the chopped baby spinach and cook for 1-2 minutes until wilted.
Season with salt and freshly ground black pepper to taste.
Remove from heat and serve immediately.