Preheat oven to 350 degrees F. Spray an 8x8 baking dish with nonstick cooking spray.
Cook and drain the lasagna noodles according to the directions on the box. I usually boil the noodles 1 minute less than it recommends since they will also be baked.
Heat a nonstick skillet over medium-high heat and add the ground beef. Break up the meat until it is browned. Drain any grease.
Season the ground beef with the taco seasoning and add 1/4 cup water. Stir to combine and let the meat cook for 2 minutes.
Add 1 cup of the salsa and 1/2 cup of the diced tomatoes (with liquid) to a small mixing bowl. Stir together and set aside.
Pour the remaining salsa and diced tomatoes (with liquid) into the meat mixture. Bring the mixture to a simmer and cook for 5 minutes, stirring occasionally. Let the meat mixture cool slightly.
Add 1 cup of fat-free cottage cheese and an egg to a small bowl. Stir together to combine the mixture.
Add a couple spoonfuls of the salsa mixture to the bottom of the baking dish.
Lay out the cooked noodles on a clean surface. Add a couple of tablespoons of the cottage cheese mixture over each noodle. Next, add a couple of tablespoons of the meat mixture to each lasagna noodle.
Roll the lasagna noodle up starting at the bottom. Place the filled noodle in the baking dish seam side down. Continue until all six lasagna noodles are rolled up and in the baking dish.
Pour the salsa mixture over the rolled up lasagna noodles. Sprinkle the Mexican cheese over the lasagna roll ups.
Bake 30-35 minutes, or until the cheese is melted and the roll ups are heated through.