Preheat oven to 425 degrees.
Prepare the pasta al dente, according to package instructions, reserving 1/2 C cooking water.
In a dutch oven, over medium-high heat, cook the pancetta until crispy and browned.
Add the butter, Dijon mustard, lemon zest and roasted tomatoes with their oil. Sauté for 3 - 5 minutes until butter is melted.
Add the shredded chicken, spinach and grape tomatoes. Toss well to combine.
Add the cooked pasta and reserved pasta water. Season with salt and pepper. Mix well to combine.
Transfer the pasta to a large baking dish. Top with the mozzarella and grated Parmesan.
Bake for 13 - 15 minutes until cheese is melted and golden. Garnish with chives and serve immediately.
I used a local brand…Banner Butter Roasted Garlic, Basil + Parsley. So good!