Brown the sausage and mushrooms in a large skillet over medium high heat and set aside on a paper towel lined plate to drain.

Using the same hot skillet, add the spinach and cook down for 3-4 minutes or until wilted.

Add the spinach to the sausage plate and pat firmly with more paper towels to release extra moisture.

Combine the sausage, spinach and mushrooms in a medium bowl and set aside.

Combine the mozzarella, Italian cheese, ricotta, and beaten egg in a medium bowl, stirring well to combine.

Stir in 1/4 cup grated Parmesan to the cheese mixture, and set aside.

Turn the slow cooker on HIGH.

Spray the slow cooker with cooking spray and spread 1 cup of the tomato sauce in the bottom.

Arrange 3 noodles in a criss cross fashion over pasta sauce mixture (this is easier with an oval slow cooker but I made it work)

Top with 1 cup of the cheese mixture – spread with a spoon – followed by 1 cup of the spinach mixture.

Repeat the layers, ending with spinach mixture.

Arrange 3 noodles over spinach mixture and top with the remaining 1 cup cheese mixture and 1 cup pasta sauce.

Place remaining 3 noodles on top.

Spread the remaining pasta sauce over noodles.

Sprinkle with the remaining 1/2 cup of Parmesan cheese.

Cover and cook on HIGH 5 hours or until done.