In a large skillet, heat the olive oil and cook the peppers and onions until tender.
Add the ground beef, season with salt, pepper, and granulated garlic.
Drain off excess grease.
Stir in the tomato sauce and simmer for 5 minutes.
In a mixing bowl, combine 1 cup of the mozzarella cheese with the grated and ricotta cheeses. Mix until well combined.
The remaining mozzarella cheese will be for the top of the lasagna just before serving so place that back in the refrigerator.
Spoon a fourth of the meat sauce into the bottom of the slow cooker.
Break 5 noodles and place them on top.
Spread half the cheese mixture on top of the noodles. Repeat the layers, ending with sauce on the top.
Set the slow cooker to low, cover and cooker for 4-6 hours until the noodles are tender.
About 10 minutes before serving, top with remaining mozzarella cheese, cover and let stand until the cheese is melted.