Preheat your oven to 375°F (190°C) and grease a 9x13 inch baking dish.
In a large mixing bowl, combine the cooked macaroni, diced tomatoes (with juices), shredded cheddar cheese, shredded chicken, frozen mixed vegetables, and sour cream.
Add garlic powder, onion powder, paprika, salt, and pepper to the mixture. Stir everything together until well combined.
Spread the mixture evenly into the prepared baking dish.
In a small bowl, combine breadcrumbs with a drizzle of olive oil (about 1 tablespoon) to help them crisp up in the oven. Sprinkle this over the top of the casserole.
Bake in the preheated oven for 25-30 minutes, or until the casserole is bubbly and the top is golden and crispy.
Remove from the oven and let it cool for 5 minutes before serving.
Notes
Let it cool for a few minutes before serving for better slicing.