Use a paper towel to pat exterior of chicken dry. Generously salt the entire surface and let rest at least 30min to overnight (uncovered in the fridge).
Preheat oven to 450F and prep butternut squash by applying 1 Tbsp oil, salt, and pep to cut sides. Do the same to the garlic and shallot. Place the shallot and garlic inside the open space of the squash. Roast in the oven for 50-60min, until soft.
Roast the chicken at the same time as the squash, cooking until a thermometer reads 160F (or, again, just use a rotisserie).
Once the squash and chicken are nearly done, chop onion and cook pasta.
Heat large pot over medium heat and add remaining Tbsp of oil. Add onion and sauté. Add roasted shallot and garlic and flesh of the squash.
Add 4 cups chicken stock and herbs. Bring to a simmer and cover, cooking for 15-20min.
Remove herbs and blend sauce until thicc and creamy. Add spinach, pasta, and chicken. Mix until well-combined.
Divide among 7 serving containers.