Spray skillet with cooking spray, heat over medium heat until hot.
Saute onion and garlic 3 to 4 minutes over medium heat until hot.
Saute onion and garlic 3 to 4 minutes; add mushrooms and saute 5 minutes.
Cook over medium heat until mixture is dry, about 5 minutes, stirring occasionally.
Season to taste with salt and pepper.
Saute green onions in butter in medium saucepan until tender.
Stir in flour and rosemary and thyme; cook 1 to 2 minutes, stir.
Add milk and heat to boil, stirring constantly, until sauce thickens.
Mix in spaghetti sauce, cream cheese, and 1/2 cup Parmesan cheese; cook, stir, until sauce is hot and cream cheese is melted, approx.
6 minutes.
Add salt and a pepper.
Stir in 1 cup sauce into mushroom mixture.
Spread about 1/2 cup remaining sauce into baking pan; arrange noodles in pan, overlapping edges.
Spoon 1/2 mushroom mixture and the sweet potato over noodles and spread in 1 cup sauce.
Repeat layers, ending with layer of noodles and 1 cup sauce.
Sprinkle with remaining 1/4 Parmesan cheese.
Bake lasagne, loosely covered, at 350 degrees until noodles and sweet potato are tender, 50 to 60 minutes.
Let cool before serving.