Cook pasta in salted water to al dente according to package directions. Drain and set aside.
Preheat oven to 375°F. Spray a 9×13-inch baking dish with cooking spray.
In a large skillet over medium heat, melt 3 tablespoons butter with olive oil. Add onion, carrots, and celery. Cook 6 to 8 minutes, stirring often, until softened.
Add garlic and cook 30 seconds.
Sprinkle flour over the vegetables. Stir constantly for 1 to 2 minutes.
Slowly pour in chicken broth while stirring. Add milk (and cream, if using).
Add salt, pepper, poultry seasoning, thyme, parsley, and sage. Bring to a gentle simmer and cook 4 to 6 minutes, stirring often, until thickened.
Stir in chicken, peas, and corn. Warm through 2 minutes.
Add cooked pasta and stir until coated. Pour into baking dish.
Mix panko, parmesan, and melted butter. Sprinkle evenly over the top.
Bake uncovered 18 to 22 minutes, until bubbly and golden. Rest 5 to 10 minutes before serving.
If using baked pie crust pieces, scatter them over each serving right before eating.