Begin by cleaning the whole squid thoroughly under cold running water, ensuring there are no residuals. Separate the tentacles from the tubes, then finely chop the tentacles. Pat the squid tubes dry with paper towels, ready for stuffing, and set them aside to focus on making the delicious filling for your Baked Italian Stuffed Calamari.

In a large oven-safe skillet, heat a drizzle of extra virgin olive oil over medium heat. Add the ground sweet Italian sausage, breaking it up with a spatula. Cook for about 5-7 minutes or until browned and cooked through. Stir in minced garlic and crushed red pepper flakes, cooking for an additional minute until fragrant.

Transfer the cooked sausage mixture into a food processor. Add in the chopped tentacles, plain breadcrumbs, grated Parmesan cheese, chopped parsley, kosher salt, and black pepper. Pulse until well combined, creating a flavorful stuffing.

Using a small spoon or your fingers, gently fill each squid tube with the sausage mixture. Be sure to pack it in without overstuffing, leaving a small space at the top to prevent bursting.

Reheat the same skillet over medium heat and add a bit more olive oil if necessary. Carefully place the stuffed calamari in the skillet, searing them for 1-2 minutes on each side until they develop a light golden brown color.

Now, pour a generous amount of Italian gravy or marinara sauce over the seared calamari in the skillet. Preheat your oven to 350°F (175°C) and transfer the skillet directly into the oven. Bake for 15-20 minutes, or until the sauce is bubbling and the calamari are cooked through and tender.