Coat the inside of the crock pot with cooking spray.
Layer ingredients in the crock pot.
1 cup of pasta sauce on the bottom of the crock pot.
Add a layer with 4 lasagna noodles. Break them to fit the shape of the pot as needed.
Add a layer of Ricotta cheese with 1/3 of the cheese.
Add a layer of 1/2 cup of Mozzarella cheese.
Spoon on a layer of 1/3 of the cooked ground meat.
Spread 1/3 of the pepperoni next.
Blanket the meat with a layer of spinach leaves.
Repeat the layering process. Pasta sauce, noodles, Ricotta cheese, Mozzarella cheese, ground beef, pepperoni and finally spinach 2 more times.
Add a final layer of pasta sauce and then the remaining Mozzarella cheese.
Cover the crock pot and cook on low for 6. The noodles should be tender.