Wash zucchini carefully under clean water. Slice them into thin rounds. Sprinkle a little salt and let them sit for 10 minutes. This removes extra moisture and improves texture during baking.

Heat olive oil in a skillet over medium heat. Add chopped onions and cook until soft and light golden. Add garlic and stir for one minute until fragrant and slightly golden.

Add sliced zucchini to the skillet. Cook for 5 to 7 minutes until slightly tender. Do not overcook because zucchini will continue cooking in the oven during baking.

In a large bowl, mix sour cream and cream of mushroom soup. Stir until smooth and creamy. This will create the rich base for Paula Deen zucchini casserole recipe.

Add cooked zucchini, onions and garlic into the creamy mixture. Stir well so everything is evenly coated. Add salt and black pepper for balanced flavor and seasoning.

Grease a baking dish with butter or oil. Pour the zucchini mixture into the dish evenly. Spread it out so it bakes properly and cooks evenly in the oven.

Sprinkle shredded cheddar cheese over the mixture. Then add breadcrumbs and Parmesan cheese on top. This creates a crispy golden crust after baking.

Preheat oven to 375°F (190°C). Bake for 30 to 35 minutes until the top is golden brown and bubbly. Remove carefully and let it rest for 5 minutes before serving.