To prepare the squash – cut them in half, remove the seeds at the bottom, lay them on a foil-lined baking tray skin side down, drizzle with olive oil and sprinkle with salt and pepper, make sure the flesh side is fully coated in the oil and seasoning, then flip the squash flesh side down skin side up and bake for about 20 minutes or until the flesh is roasted and soft.
While the squash is baking, to a non-stick pot over medium heat add the chopped pieces of prosciutto. Let it crisp for about 1 minute or 2, stirring occasionally then remove the prosciutto and leave to the side with the grease still in the pot. Next add the butter, crushed garlic clove, and onion. Saute over medium-low heat for about 5-6 minutes or until the onion is soft.
Remove the garlic, add in the barley and toast the grain for about 3 minutes, stirring often to avoid burning. Then add in the stock and simmer for 20 minutes or until the barley is fully cooked but still chewy on the inside.
Once the barley is almost finished the squash should be done roasting. Add the flesh of the squash on the top portion into the pot with the barley. Leaving about 1/4 inch of flesh along the skin and making space to stuff with the barley. To the pot with the barley and squash also add the salt, pepper, parmesan, and walnuts.
Take the barley mixture and stuff it into the squashes. Then sprinkle on a little more parmesan on top and dollop with goat cheese. Broil for 5-6 minutes or until the cheesy crust becomes golden brown and bubbly.
Once the squashes are done top with the fresh parsley and sprinkle with the crisp prosciutto.