Fill a large pot with lightly salted water and bring to a rolling boil over high heat. Once the water is boiling, stir in the macaroni, and return to a boil. Cook the pasta uncovered, stirring occasionally, until macaroni is cooked through but still slightly firm, about 8 minutes. Drain well.
Combine the cottage cheese, sour cream, butter, and cooked macaroni in a large baking dish. Stir in the Cheddar cheese. Arrange the tomatoes on top, then pour the tomato liquid over the casserole. Season with salt and black pepper.
Bake in the preheated oven for 20 minutes, then mix the macaroni and cheese thoroughly. Continue to bake until lightly browned and bubbly, about 15 minutes more.