Heat a large skillet over medium heat. Add ground turkey, mushrooms, green pepper and onion and cook, stirring occasionally, until turkey is browned, about 10 minutes. Drain turkey mixture; return to skillet. Scramble 6 eggs in a bowl with some salt and pepper to taste and add to skillet along with the tomato and stir until eggs are set. Remove from heat; stir in 1 1/2 cups mozzarella cheese and set aside.

In a large bowl, combine spinach, ricotta, dried basil, remaining egg, remaining 1/2 cup cheese and salt and pepper to taste. Set aside.

Lightly brush a 13-by-9-inch baking dish with butter (or spray with cooking spray). Layer 10 sheets of fillo dough into prepared pan, brushing each sheet with butter (or spraying with cooking spray). Top with half of the turkey mixture. Layer with another 10 sheets of butter-brushed fillo dough; top with ricotta mixture. Layer another 5 sheets of butter-brushed fillo dough and top with remaining turkey mixture. Top with 5 more sheets of butter-brushed fillo dough.

At this point, you can either cover the casserole and place it in the fridge overnight, or you can bake it right away. If storing overnight, take casserole out of the fridge 15 minutes before baking. Heat oven to 350 degrees F and bake 50 minutes to 1 hour or until golden and warmed through. If baking right away, heat oven to 350 degrees F and bake 40-50 minutes or until golden. Slice into squares and serve warm.