Cook shells according to package directions. Drain and rinse.
In a large skillet over medium-high heat cook burger until no longer pink inside. Drain if needed. Add 1 1/4 cup water to the burger and then mix in the tomato paste, tomato sauce, and Sloppy Joe Seasoning. Reduce heat to simmer and continue cooking for about 10 minutes.
Spray a 2 1/2 quart casserole dish with cooking spray and spread 1/ 2 of the shells over the bottom followed by the cottage cheese, and then the meat mixture.
Repeat the layers and top with the cheddar cheese.
Bake for 35-40 minutes or until cheese is melted and casserole is bubbly. Serve hot.