01 -
Preheat oven to 350°F (175°C). Spray a 9x13 inch baking dish with nonstick cooking spray.
02 -
Bring a large pot of water to boil. Cook the jumbo shells according to package directions until al dente. Drain well and set aside to cool slightly.
03 -
While pasta cooks, brown the ground beef over medium-high heat in a large skillet. When it's about halfway browned, add the diced onion and continue cooking until the beef is fully browned and the onions are soft. If needed, drain excess grease.
04 -
Add the taco seasoning and water to the ground beef mixture. Simmer for 10 minutes, allowing the flavors to combine and the liquid to reduce. Stir in the salsa and remove from heat. Let cool for a few minutes.
05 -
Once slightly cooled, stir half of the cheddar cheese and half of the Monterey Jack cheese into the beef mixture.
06 -
Spoon the seasoned ground beef mixture into the cooked pasta shells and arrange them in a single layer in the prepared baking dish.
07 -
Top the filled shells with the remaining cheese, drained Rotel tomatoes, and minced jalapeño. Cover with foil and bake for 20 minutes. Then uncover and bake for an additional 5 minutes until cheese is bubbly and lightly browned.
08 -
Sprinkle with additional minced jalapeño or green onions if desired. Serve promptly for best results.