01 -
Turn the oven on to 350°F (175°C). Grab a 9x13 inch baking pan and coat it with a nonstick spray.
02 -
Fill a big pot with water and bring it to a rolling boil. Cook those big shells as directed on the package until they’re just tender. Strain them, let them cool a bit, and set them aside.
03 -
As the pasta boils, cook the ground beef in a deep pan over medium-high heat. When it’s about halfway browned, toss in the diced onion and cook until the beef is browned all the way through and the onions have softened. Get rid of any extra grease if necessary.
04 -
Mix the taco spices and water into the beef and onion mixture. Let it simmer for 10 minutes so the flavors blend and the liquid mostly evaporates. Then stir in the salsa and take the pan off the heat. Give the mixture a few minutes to cool down.
05 -
Once the beef mixture has cooled down a little, stir in half the cheddar and Monterey Jack cheese.
06 -
Scoop the beef filling into the pasta shells and lay them neatly in a single layer in the sprayed baking dish.
07 -
Scatter the remaining cheese on top of the shells, then add the drained Rotel tomatoes and minced jalapeño. Cover the dish with foil and bake for 20 minutes, then take off the foil and bake an extra 5 minutes to get the cheese bubbly and slightly golden.
08 -
If you want, sprinkle the dish with extra jalapeños or green onions for a nice garnish. Serve right away to enjoy it best.