Preheat oven to 350º F and lightly grease a 9×13 baking dish.
Brown beef in a large skillet and drain off excess oil, then stir in taco seasoning and set aside.
In a medium bowl, mix egg with ricotta cheese until well combined. Set aside.
Place 4 lasagna noodles in bottom of baking dish. Spread 1/3 of ricotta over noodles, then evenly spoon 1/3 of ground beef mixture over ricotta. Evenly spread 1/3 of salsa over beef, then layer 1/3 of cheddar cheese over beef. Repeat steps, finishing with cheddar cheese.
Cover with foil and bake for 30-40 minutes, or until lasagna is heated through. Let cool 5-10 minutes, top with sour cream and fresh cilantro, (optional), serve and enjoy!