Brown ground beef with onion and minced garlic. Add salt and pepper and Italian seasoning.
Add marinara and stir to combine.
In a medium to large bowl, add softened cream cheese and egg. Mix to combine. This might take a couple minutes.
Mix into the cream cheese mixture, Parmesan cheese and 1/2 the mozzarella.
Add the thawed spinach to the bowl.
Stir to combine.
Add the ground beef mixture to the cheese mixture. Stir to combine.
Spray a casserole dish with non-stick spray. Scoop the ground beef, cheesy mixture to the prepared dish. Top with the remaining mozzarella cheese.
Bake at 350 degrees for 25-35 minutes, until hot and bubbly.
