If freezing, add chicken, sun-dried tomatoes, garlic, 1 cup broth, Italian seasoning, paprika, red pepper flakes, salt, and pepper to a freezer bag. Keep orzo, 2 cups of broth, dairy, and spinach separate for baking day. Freeze flat for up to 3 months and thaw overnight in the fridge before baking.
To bake, preheat the oven to 375°F. Add the chicken freezer marinade, dry orzo, remaining broth, milk, cottage cheese, parmesan, and spinach to a greased 9x13-inch baking dish.
Cover tightly with foil.
Bake 35 to 40 minutes, stirring once halfway through, until orzo is tender and chicken is cooked through.
Let sit 5 to 10 minutes to thicken before serving.