Preheat the oven to 350°F. Lightly spray a 13 x 9 baking dish with cooking spray.
Place squash halves skin side down in a large skillet. Add water until 1/2 inch up sides. Simmer for about 7-8 minutes. Remove from the water set aside to cool.
In a small skillet, saute the diced onion in a light drizzle of olive oil over medium high heat until translucent. Season with salt and black pepper to taste.
Add the Italian sausage cooking until brown. Add, garlic and spinach. Sauté just until the spinach begins to wilt then remove from the heat.
In the same pan, melt 1 tablespoon of butter. Add the cubed bread and sauté for 1-2 minutes until golden. Sprinkle the Italian seasoning over the bread cubes while toasting.
Add the bread cubes, spinach and sausage mixture to a mixing bowl. Mix together with 1 cup of shredded Italian cheese blend cheese and 2 tablespoons of grated Parmesan cheese. Set aside.
Use a teaspoon to remove the seeds from the steamed squash. Place side by side in the baking dish. Season with salt and pepper to your taste. You can drizzle them with melted butter, if you like for added flavor.
Divide the sausage filling evenly between squash halves. Sprinkle tops with remaining cheese.
Bake for 30-35 minutes until the filling is golden and the squash is fork tender and cooked through.
Sprinkle with chopped parsley, if desired. Serve immediately.
a) Use a sharp knife to cut a flat piece from the backside of the squash to stabilize it. This will prevent the squash from rolling and it will remain upright while cooking. b) Choose a blend of shredded Italian cheese in the flavors you enjoy.