In a medium bowl, combine the cottage cheese, shredded mozzarella, kosher salt, and black pepper until evenly mixed.
Spoon 1 cup of the marinara sauce into the bottom of the slow cooker and spread into an even layer.
In a separate bowl, toss the uncooked ziti shells with the remaining marinara until the pasta is well coated.
Layer the coated pasta, sliced zucchini, and cheese mixture in the slow cooker, repeating layers and finishing with the cheese mixture on top.
Cover and cook on low for 2 hours, or until the pasta is al dente and zucchini is tender.
Spoon portions onto plates and sprinkle each serving with grated Parmesan before serving.