Preheat your oven to 350°F (177°C).

Bring a large pot of salted water to a boil. Add jumbo shells and cook about 10 minutes until al dente. Drain and rinse under cold water.

In a large skillet over medium-high heat, cook the ground beef and diced onion until browned and the onion is translucent. Drain any excess grease.

Stir the taco seasoning into the beef. Add the cream cheese and mix until the filling is smooth and creamy.

In a small bowl, whisk together the enchilada sauce and salsa.

Pour half of the sauce mixture into a 9x13-inch baking pan. Spoon the beef mixture into each shell and arrange them seam-side up. Pour the remaining sauce evenly over the shells.

Cover the pan tightly with aluminum foil and bake for 30 minutes.

Remove the foil, sprinkle cheddar and mozzarella over the shells, and return to the oven for 8–10 minutes until the cheese melts and bubbles.

Let the pan rest for 5 minutes before serving. Top with your favorite taco toppings if desired.