Preheat the oven to 400°F (200°C, or gas mark 6).

Cut the spaghetti squash in half lengthwise and use a spoon to scoop out all the seeds. Rub the inside of each half of the squash with the avocado oil and place the halves in a deep, oven-safe 12-inch (30-cm) skillet or a 9 x 7–inch (23 x 18–cm) casserole dish. Roast the squash for 40 to 45 minutes, or until it is fork-tender. Use a fork to pull the strands of noodles away from the spaghetti squash rind. Scatter the spaghetti squash on the bottom of the skillet or a casserole dish and set it aside.

To prepare the shrimp, peel, devein and butterfly the shrimp, leaving the tail on. Toss the shrimp with the salt, pepper and lemon zest. Set it aside.

To prepare the butter sauce, add the ghee, lemon juice, crushed red pepper flakes and garlic to a small bowl. Whisk to combine.

To prepare the crust, toss together the Parmesan cheese and the parsley. Set it aside.

Arrange the shrimp on top of the spaghetti squash in a single layer, cut side down with the tail pointing up and toward the center of the dish. Pour the butter sauce all over the shrimp. Transfer the baking dish to the oven and bake for 15 minutes, or until the shrimp is pink and cooked through.

Remove the dish from the oven and turn the oven to broil. Scatter the Parmesan cheese and parsley crust on top of the shrimp and return the dish to the oven. Broil for 2 to 3 minutes to melt the cheese. Let the dish rest for 5 minutes before serving.