Preheat oven to 375F. Roast thinly sliced squash tossed with olive oil and salt for 20 minutes.
In a skillet, brown the ground beef until fully cooked. Drain excess fat and set aside.
Prepare a simple white sauce by melting butter, whisking in flour, and slowly adding milk until thickened.
In a bowl, mix ricotta cheese with chopped fresh spinach and a pinch of salt.
Assemble by layering white sauce, noodles, ricotta mixture, beef, roasted squash, and mozzarella in a 9x13 baking dish. Repeat layers.
Cover with foil and bake for 30 minutes. Remove foil and bake another 15 minutes until golden brown.
Toss mixed greens and orange segments with a light vinaigrette to serve alongside the baked pasta.