Grease a 9x13 inched baking dish or large casserole pan with butter or a drizzle of oil, set aside.
Add pasta to a pot with boiling water. Add a drizzle of oil, and stir. Cook per package instructions, aiming for al dente, or 1-2 minutes shy from what the package cooking time suggests, as it will be cooking in the oven as well.
Once pasta is cooked, drain it and add it to a large bowl.
In the meantime thaw the frozen veggies under warm water and slice the mushrooms.
Cook the Veggies:
Add two tablespoons of olive oil to a large skillet over medium heat. Once the oil is hot add onion and garlic, cook stirring for 1 minute.
Add sliced mushrooms, dried parsley, thyme, oregano, pepper flakes, salt and pepper.
Stir and cook for about 5 minutes, until the mushrooms start to get softer.
Remove from heat and set aside.
Add cooked and drained pasta to a large bowl.
Add shredded turkey meat, condensed cream of mushroom soup, sour cream, grated cheese, thawed mixed veggies and the cooked mushroom mix. Stir to combine.
If the mixture needs more liquid, add 1/4 cup at a time and stir well to combine.
Transfer the mixture to the prepared baking dish or casserole pan.
Buttery Cracker Topping:
In a medium bowl, combine cracker crumbs with melted butter, until well blended.
Spread the crumb mixture on top of the casserole.
Sprinkle the remaining 1 cup of cheese on top. Distribute evenly.
Bake for 30-40 minutes or until mixture is bubbly, cheese is fully melted and the top is golden brown.