Step 1

Preheat oven to 400°F.

Step 2

Use a large knife to cut the spaghetti squash lengthwise from stem to tail. Lightly coat the flesh with cooking spray, and place cut-side down on a baking sheet. Bake for 30 to 40 minutes, under tender. Let sit until cool enough to handle.

Step 3

Meanwhile, heat oil in a large skillet over medium heat. Add shallots and garlic; cook 3 minutes, until soft. Whisk in flour, and cook 2 minutes. Gradually stream in milk, and whisk until smooth. Gently simmer until thickened, about 3 to 4 minutes. Whisk in lemon juice, Parmesan cheese, salt, and pepper. Remove from heat and stir in shredded chicken.

Step 4

Scrape out and discard the seeds of the spaghetti squash. Use a fork to scrape out all of the spaghetti-like strands, and stir them into the chicken Alfredo mixture.

Step 5

Fill empty squash boats evenly with chicken Alfredo mixture, and sprinkle mozzarella cheese overtop. Return to oven and bake for 10 minutes. Set broil to HIGH and broil for 2 minutes, or until cheese is golden in some spots. Remove from oven and garnish with fresh parsley.