Begin by boiling the gnocchi according to the package instructions. Once they float to the surface, they're done. Drain them well and set aside.
In a large skillet, heat the olive oil over medium heat. Add the minced garlic and sliced mushrooms. Sauté until the mushrooms release their moisture and become tender.
Add the fresh spinach to the skillet. Cook until wilted, stirring occasionally.
Pour in the heavy cream and bring to a simmer. Allow it to cook for a few minutes until it slightly thickens.
Stir in the shredded mozzarella and grated Parmesan cheeses. Continue to cook, stirring, until the cheeses melt and the sauce becomes smooth and creamy.
Add the cooked gnocchi to the skillet. Gently toss to coat the gnocchi in the cheese sauce.
Season with salt and freshly ground black pepper to taste. Serve hot, garnished with additional Parmesan cheese if desired.