Preheat the oven to 425°.

Boil the conchiglie pasta until al dente in a large pot of boiling salted water, which takes about 8-9 minutes while gently stirring. Remove the noodles from the water, chill in an ice bath and then spread out on a sheet tray lined with parchment paper and set to the side.

Add the olive oil to a large rondeau pot over medium heat and cook the onions until lightly browned, which takes about 10 minutes. Next add in the garlic and cook for 1 minute.

Add in the Italian sausage and ground beef and cook until lightly browned and cooked through. Make sure to cut it down into small pieces.

Mix in the baby spinach just until wilted and then transfer the mixture to a large plate and slightly spread everything out and chill in the refrigerator for about 30 minutes.

Once cool transfer to a large bowl along with the basil, ½ the amount of small diced mozzarella, ricotta, 1 cup of parmesan cheese, large egg, and salt and pepper, and mix until completely combined.

Using a small spoon or a piping bag stuffed with the meat and cheese filling, stuff each shell until they are completely full. I was able to get 28 stuffed shells.

Evenly pour the pomodoro sauce into the bottom of a 13x9 casserole dish until it is coated.

Next, randomly bour ¾ of the bechamel sauce on top of the tomato sauce. See Video.

Line up as many stuffed shells as possible over the sauces. You may need to cook some in a separate dish if they all do not fit.

Sprinkle on remaining small diced mozzarella and ½ cup of grated parmesan all over the top and bake at 425° for 25-30 minutes or until browned on top.

Garnish with optional chopped parsley or basil.