Step 1

Spray the inside of the slow cooker with cooking spray.

Step 2

In a medium bowl, combine the ricotta cheese, egg whites, Parmesan cheese, 1/2 cup mozzarella, salt, and pepper.

Step 3

Cover the bottom of the slow cooker with about half of the ziti noodles.

Step 4

Pour about 2 cups of spaghetti sauce over the top and spread evenly with a spoon.

Step 5

Distribute about half of the ricotta mixture on top of the sauce and spread evenly.

Step 6

Place the mushrooms on top of the ricotta, and then the spinach.

Step 7

Place remaining noodles on top, then spread another 2 cups of sauce, then spread the remaining ricotta cheese mixture.

Step 8

Pour the remaining sauce on top and spread evenly.

Step 9

Cook on low for about 4 hours. No more than 5!

Step 10

About 5 minutes before serving, remove lid and sprinkle the remaining mozzarella cheese over top. Replace the lid and let the cheese melt before serving.