Begin by prepping the vegetables. Chop the onion, bell peppers, and zucchini, and mince the garlic.
In the Crockpot, layer the sliced Italian sausage, followed by the chopped onion, minced garlic, diced tomatoes (with juice), kidney beans, corn, bell peppers, and zucchini.
Sprinkle the dried oregano, basil, smoked paprika, salt, and pepper over the top of the layered ingredients.
Stir gently to mix the ingredients, ensuring the spices are evenly distributed.
Cover the Crockpot with its lid and set it to cook on low heat for about 6 hours or on high heat for 3 hours.
Once the cooking time is complete, check for doneness, ensuring the sausage is cooked through and the vegetables are tender.
If desired, sprinkle shredded cheddar cheese on top during the last 15 minutes of cooking to allow it to melt and become bubbly.
Serve the casserole hot, straight from the Crockpot, and enjoy!