Boil the large pasta shells. Begin by heating a large pot of water on the stove to medium-high. Once the water is boiling, add the large pasta shells and cook as directed until they are al dente. It’s crucial not to overcook them as they will finish cooking in the oven, which could lead to mushy shells. Once cooked, drain the pasta and toss it in a drizzle of olive oil to prevent sticking.
Brown the Italian seasoned ground beef. In a large skillet, heat the remaining olive oil over medium-high heat until it shimmers. Add the ground beef along with the onion, red pepper, garlic, salt, pepper, parsley, and oregano. Cook this mixture for about ten minutes, stirring regularly to break down the beef. Look for the meat to turn a rich brown color and for the onions to become translucent. Remove from heat, and strain the mixture on a plate lined with a paper towel to absorb any excess grease.
Prepare the baking dish. Preheat your oven to 350 degrees Fahrenheit. Grab a medium-sized baking dish and cover the bottom with a cup of pasta sauce. This step locks in moisture and prevents the shells from sticking or burning.
Mix together the stuffed pasta filling. In a large bowl, gently combine the cooked beef mixture with the ricotta cheese, Parmesan cheese, and one cup of pasta sauce. Taste the mixture and adjust the seasoning if necessary with some extra salt and pepper. You want the filling to be flavorful as it will carry the entire dish.
Stuff every cooked shell. Carefully grab each cooked shell and fill it with the beef and cheese mixture. Be generous with the filling! Place each stuffed shell into the baking dish, lined up neatly. Once all the shells are filled, top them with the remaining pasta sauce and sprinkle a generous amount of mozzarella cheese on top.
Bake the stuffed shells. Place the baking dish in the preheated oven and bake for about twenty minutes or until the cheese is melted and bubbly. The top should have a beautiful golden color. It’s the perfect time to let the layers of flavor come together.
Let it cool before serving. Once baked, remove the dish from the oven and let it cool for at least ten minutes. This allows the flavors to meld and makes serving easier. If you’re waiting to serve it to guests, cover it with tin foil to keep it warm.