In a large pot of boiling salted water, cook pasta, stirring occasionally, until al dente according to package directions. Drain; reserve ½ cup pasta water.
Meanwhile, in a blender, blend marinara, cottage cheese, Parmesan, and oil until smooth.
Return pasta to pot and add sauce and ¼ cup reserved pasta water. Toss, adding more pasta water as needed, until pasta is coated and sauce is warmed through.
Divide pasta among bowls. Top with Parmesan.
