In a large skillet over medium heat, add the lean Italian turkey sausage. Break it apart with a wooden spoon, cooking for about 7-10 minutes, or until browned and fully cooked. Ensure to drain off any excess fat.

Add the diced onion and red bell pepper to the skillet with the sausage, stirring occasionally for about 4-5 minutes until they soften. Incorporate the minced garlic and thawed chopped spinach, mixing well to combine all the flavors. Cook for an additional 2-3 minutes.

In a large mixing bowl, crack the eggs and whisk them together thoroughly. Pour in the almond milk, followed by dried basil, salt, and pepper. Continue whisking until everything is well combined.

Preheat your oven to 350ºF (175ºC). Grease a 9x13-inch baking dish with cooking spray. Evenly layer the shredded hash brown potatoes at the bottom of the dish. Spoon the sausage and vegetable mixture over the potatoes, then pour the egg mixture over the top.

Cover the casserole with aluminum foil, and place it in the preheated oven. Bake for 1 hour. After that, remove the foil and bake for an additional 15 minutes until the top is golden brown and the center is firm to the touch.

Allow the casserole to cool for about 5-10 minutes before slicing. Cut into squares, and serve warm.