Start by chopping your onions, mushrooms, and spinach, and mincing the garlic. Season the chicken thighs with salt, pepper, and paprika. Boil the gnocchi according to package instructions, then set aside.
Heat 2 tablespoons of butter in a large skillet over medium-high heat. Sear the chicken thighs for 5–10 minutes on each side until golden brown. Transfer to a plate and keep warm while preparing the sauce.
Add the remaining butter to the skillet, then toss in garlic, onions, mushrooms, and Italian seasoning. Sauté for 3–4 minutes until the onions are translucent and mushrooms tender.
Whisk in chicken broth for one minute until combined, then add half and half. Gradually mix in mozzarella until melted and the sauce thickens slightly.
Stir in the drained gnocchi and spinach, adjusting seasoning with salt and pepper. Nestle the chicken back into the skillet, allowing it to simmer for a few minutes until heated through.