Brown the sausage in a large skillet over medium heat for 5-7 minutes, crumbling as it cooks. Drain excess fat.

Add spinach to the skillet and cook for an additional 2-3 minutes until wilted.

In a mixing bowl, whisk together eggs, milk, salt, pepper, and garlic powder.

Preheat oven to 375°F (190°C). Layer lasagna sheets, sausage-spinach mixture, cheese, and egg mixture in a greased baking dish.

Cover with foil and bake for 30 minutes, then remove foil and bake for another 10-15 minutes until cheese is bubbly and golden.

Let lasagna rest for 10 minutes before serving.