Start by bringing a large pot of salted water to a boil. Add the 12 ounces of elbow macaroni and cook according to package instructions until al dente. Once cooked, drain the macaroni in a colander and set aside.
In a mixing bowl, combine the 1 cup of cottage cheese, 1 1/2 cups of shredded cheddar cheese, and the optional 1/2 cup of unflavored protein powder. Mix well until the ingredients are fully blended.
In a saucepan, whisk together the 1 cup of milk, 1 tablespoon of cornstarch, 1/2 teaspoon of salt, and 1/2 teaspoon of pepper. Heat over medium-low heat, stirring until the mixture thickens slightly, about 3-5 minutes.
Add the cooked macaroni to the cheese mixture and pour in the creamy milk mixture. Stir well until all the pasta is coated with the cheesy goodness. Continue to cook on low heat for another 5 minutes, allowing the flavors to meld together.
You can serve the Protein Mac And Cheese right away for a creamy dish. If you prefer a baked version, transfer the mixture to an oven-safe dish, sprinkle a bit more shredded cheddar cheese on top, and bake at 350°F (175°C) for about 15-20 minutes, until bubbly and golden.