Preheat and prep: Heat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with butter or nonstick spray.
Cook the pasta: Boil the macaroni in well-salted water until just shy of al dente. Stop 1–2 minutes early so it doesn’t turn mushy in the oven. Drain and set aside.
Blend the sauce: In a blender or food processor, combine cottage cheese, 2 cups of the shredded cheddar, milk, eggs, yogurt or sour cream (if using), Dijon, garlic powder, onion powder, paprika, 1/2 teaspoon salt, and 1/4 teaspoon black pepper.
Blend until mostly smooth. Taste and adjust seasoning.
Combine with pasta: In a large bowl, toss the warm pasta with melted butter. Pour the cottage cheese mixture over it and fold gently to coat.
Assemble the casserole: Spread half the pasta in the baking dish.
Sprinkle with 1/2 cup cheddar. Add the remaining pasta and top with the rest of the cheddar.
Add the crunch: Mix bread crumbs with Parmesan (if using) and a drizzle of melted butter. Scatter evenly over the top for a crisp finish.
Bake: Bake uncovered for 25–35 minutes, until the edges are bubbling and the top is golden.
If needed, broil for 1–2 minutes at the end to brown the crust—watch closely.
Rest and serve: Let the casserole sit for 8–10 minutes to set. Scoop and serve warm.