Bring large pot of lightly salted water to boil. Cook spaghetti in boiling water, stirring occasionally until "al dente" (cooked through but firm to bite), about 12 minutes. Drain.
Heat large skillet over medium-high heat. Cook and stir beef in hot skillet until browned and crumbly, 5 to 7 minutes, drain and discard grease.
Place beef in bowl and mix with spaghetti sauce.
Combine cream cheese, sour cream and cottage cheese until well blended.
Place half slices of butter into bottom of 9" x 13" casserole dish. Spread half spaghetti into dish. Top spaghetti with creamy mixture. Layer remaining spaghetti over creamy mixture. Top with remaining pats of butter. Pour ground beef mixture over spaghetti and spread to cover casserole.
Bake in preheated oven for 30 minutes.
Spread Cheddar cheese over pasta and continue baking until cheese has melted and is lightly browned, about 15 more minutes.