Preheat the Oven: Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with cooking spray to ensure the casserole doesn't stick during baking.

Combine Ingredients: In a large mixing bowl, combine the leftover stuffing, chopped turkey, and leftover cooked vegetables. Add in the mayonnaise and stir until all the ingredients are well coated and mixed together. The mayonnaise helps to bind everything and adds a creamy texture to the casserole.

Layer the Mashed Potatoes: Spread the mashed potatoes evenly over the top of the turkey mixture in the baking dish. Smooth the potatoes into an even layer with a spatula. The mashed potatoes will serve as a delicious, creamy layer on top of the casserole.

Add the Cheese: Sprinkle the shredded Cheddar cheese evenly over the mashed potatoes. This will melt and create a cheesy, golden top during baking.

Season and Bake: Sprinkle the paprika over the cheese to add a touch of color and a hint of smokiness. Place the casserole in the preheated oven and bake for about 30-35 minutes, or until the top is golden brown and bubbly. If you want an extra crispy top, you can broil the casserole for an additional 2-3 minutes, watching carefully to avoid burning.

Serve and Enjoy: Once the casserole is baked to perfection, remove it from the oven and let it rest for a few minutes before serving. Scoop out portions and enjoy your easy, comforting meal made entirely from leftovers!