Preheat oven to 350ºF. Lightly spray a 9×13-inch baking dish with cooking spray. Set aside.: The warm oven creates a consistent environment so the casserole finishes with an even, golden top and bubbling edges, and the preheated heat prevents the dish from taking too long to come up to temperature. You should notice a gentle, dry warmth filling the oven and a faint metallic hum as it cycles; this means it is ready. If the oven is not fully preheated the casserole may take longer and the topping might brown unevenly, so wait for the indicator light or use an oven thermometer to be sure.
Cook noodles according to package directions; drain.: Properly cooked egg noodles should be tender with a slight bite, not falling apart, and the steam as you drain them should smell faintly of toasted wheat, signaling they are done. Hot noodles absorb sauce more effectively, but if overcooked they will disintegrate in the bake, creating a gluey texture. A common misstep is boiling too long, so always taste a noodle near the shortest suggested time to judge doneness.
Combine noodles and cottage cheese and pour into prepared baking dish. Set aside.: When you fold creamy cottage cheese into the warm noodles, you should see small pockets of white that will melt into the pasta as it bakes, adding tang and body. The mixture should look cohesive but not soupy; if it seems watery, let it sit a few minutes so some moisture is reabsorbed. Avoid packing the dish too tightly, which can prevent even baking and result in dense areas.
In a saucepan, combine cheddar cheese soup, half-and-half, cheddar cheese, cream cheese, and butter. Cook and stir over medium heat until blended and cheeses and butter are melted. Season with salt and pepper; spoon over noodle mixture. Toss together in the dish, if desired.: As the sauce warms, you will see the cream cheese soften into ribbons, then melt into a glossy sauce; it should smell rich and slightly tangy, and small strings of melted Cheddar cheese will form as you stir. This low to moderate heat preserves a smooth emulsion, and stirring constantly prevents scorching on the pan bottom. If the sauce overheats it can separate, becoming oily, so keep the temperature moderate. When spooning the sauce, aim for even coverage so every noodle strand gets sauced.
Sprinkle with Parmesan cheese and crushed croutons. Bake, uncovered, for 15 to 20 minutes, until bubbly and golden.: The top will transform as it bakes, the Parmesan cheese melting and browning to a nutty aroma while the croutons toast to a crisp, breadcrumb cradle; look for bubbling at the edges and a warm, golden sheen on top. You should hear a faint crackle as moisture escapes, and the top will feel slightly firm when tapped. Leaving the casserole uncovered ensures the topping crisps; covering traps steam and softens the crunch, so resist the urge to cover unless you prefer a softer crust.