Place all the butternut squash sauce ingredients into a food processor or blender and puree until smooth. Taste the mixture and adjust seasoning if necessary, and also add more water if the sauce seems too thick, but make sure not to water it down too much. Set this mixture aside.
Chop up the cooked spinach and place in a large bowl. Add the ricotta, half of the mozzarella cheese, parsley, basil, eggs, salt, and pepper, and mix very well. Set this mixture aside.
Bring a big pot of water to a boil, and season generously with salt. Cook the jumbo shells for two minutes less than it states on the package (mine said to cook for 12 minutes, so I cooked them for 10). Remove the shells from the water, and rinse them thoroughly with cold running water. Now we’re ready to fill!
This recipe will make slightly more than one 9×13 pan of shells, but this is enough filling to fill all the shells, so plan to have two dishes ready.
Preheat the oven to 400 degrees F and spread each dish with about one and a half cups of butternut squash sauce in the bottom. Then fill each pasta shell with a spoonful of the herbed ricotta and place in the baking dish. Once the baking dish is full of a single layer of shells, snugly placed side-by-side, add two cups of butternut squash sauce on top to cover the pasta completely. Evenly sprinkle the remaining half of mozzarella cheese over the top, and add the parmigiano reggiano as well.
Bake for about 30 minutes, until the butternut squash sauce is bubbling and the cheese is slightly browned on top. Serve with an extra grating of parmigiano reggiano on top, and enjoy!
In order to cook the squash, simply cut the squash in half, remove the seeds, and roast in a 375 degree oven for an hour, until fork tender. Scoop out the flesh and puree as directed in the recipe.