1-First, preheat your oven to 400 degrees Fahrenheit, as this temperature ensures even cooking. Start by heating 1 tablespoon avocado oil in a large thick-bottomed pot or skillet over medium-high heat.

2-Next, sauté the chopped onion until softened, about 3 to 5 minutes, building a flavorful base for your sweet potato beef casserole.

3-Add the garlic and ground beef to the pot; break the meat into small chunks and brown for a few minutes. Stir in the Italian seasoning, chopped tomato (if using), chopped sweet potatoes, sea salt, and black pepper, then cover and cook, stirring occasionally, for 5 to 10 minutes until the sweet potatoes soften.

4-Add the baby spinach, cover, and cook until wilted, about 1 to 2 minutes. Transfer the mixture to a large casserole dish and spread it in an even layer, then sprinkle the grated cheese on top. Bake on the center rack for 15 to 25 minutes until the cheese melts and turns golden brown. Finally, serve hot, optionally garnished with chopped green onions, and store leftovers in an airtight container for up to 5 days.