Preheat the oven to 375 degrees. Prepare a deep baking dish and set aside.

In a small skillet, heat the olive oil on medium-high heat, add the garlic and champignons. Cook until soft and browned. Let cool down.

In a bowl combine the ground turkey, mushrooms, breadcrumbs and egg. Mix with your hands until well combined.

Place the meat mixture on cling film or parchment paper and pat firmly into a rectangle. 

Sprinkle the mozzarella evenly on the meat mixture and add the spinach leaves. Roll the meat up, starting from the short end until a loaf is formed. Place seam-side down in the baking dish.

Bake the meatloaf for 35-45 minutes in the preheated oven. Brush the marinara sauce over the load and bake for another 10 minutes until cooked. 

Remove from the oven and cool down slightly. Slice and serve the meatloaf!