Preheat your oven to 400°F (200°C).

In a large mixing bowl, combine ground beef, ground pork, mozzarella cheese, Parmesan cheese, egg, almond flour, garlic powder, onion powder, Italian seasoning, salt, and pepper. Mix until well blended and form into meatballs.

Place meatballs onto a lined baking sheet and bake for 20 minutes.

While the meatballs bake, heat a skillet over medium heat. Add diced bell peppers and onions and sauté for 5-7 minutes. Add fresh spinach and stir for another 2-3 minutes.

In a medium bowl, combine the sautéed vegetables with the low-sugar marinara sauce.

Spread the veggie-sauce mixture across the bottom of a baking dish. Place the baked meatballs on top and sprinkle shredded cheddar cheese over the dish.

Return the casserole to the oven and bake for an additional 15-20 minutes, or until the cheese is melted and bubbly.

Once baked, remove from the oven, let cool for a few minutes, and optionally garnish with fresh basil.