In medium bowl, stir together ricotta, egg, cumin and salt.
In a large pan over medium high heat add olive oil and cook sausage until browned. Remove from pan leaving behind any grease and browned bits.
Add butter to the pan and sauté onions until soft, about 5 minutes. Add garlic and mushrooms. Cook until mushrooms are browned, about 5 minutes. Add baby spinach and cook until wilted. Add meat back to pan and stir in ½ cup parmesan. Season to taste with salt and pepper and set aside.
In a 12x9 inch casserole dish layer ⅓ of the salsa, then 6 noodles (overlapping to cover the entire bottom), ½ the ricotta mixture, half the pork mixture and half the mozzarella.
Layer another ⅓ salsa, 6 noodles, remaining ricotta and remaining pork.
Add the last of the noodles, top with remaining salsa and the remaining mozzarella. Sprinkle the remaining ¼ cup parmesan and cover tightly with aluminum foil.
Bake covered 45 minutes.
Increase temp to 425 degrees, remove cover and cook 15 more minutes until golden and bubbly.