Heat the oven to 375°F and line a baking sheet with parchment paper.
Place the ground beef in a large mixing bowl. Add the drained spinach, chopped artichoke hearts, breadcrumbs, egg, minced garlic, Italian seasoning, salt, and black pepper.
Mix the ingredients with your hands until evenly combined, but avoid overworking the meat.
Divide the mixture in half. Press one half into a loaf shape on the prepared baking sheet, then arrange the Fontina cubes in a single line down the center.
Cover the cheese with the remaining meat mixture and seal the edges so the filling stays enclosed.
Bake for 45 to 50 minutes until the internal temperature reaches 160°F.
Remove from the oven and let the meatloaf rest for 10 minutes before slicing.