First, prepare your sauce. In a large saucepan, add the butter. Melt over medium heat, and then whisk in the flour. Cook until the raw flour is cooked out and it is golden brown, about 3-4 minutes. Whisk in the heavy cream, garlic powder, poultry seasoning, paprika, cayenne pepper, and a dash of salt and pepper. Bring the mixture to a simmer over medium heat. Allow the mixture to thicken substantially, whisking frequently. This will take 5-6 minutes. Reduce the heat to low. In very small amount (2-3 tablespoons), add the cheeses to the heavy cream mixture, whisking vigorously after each addition until all of the cheese has been added and the sauce is silky smooth. Leave the sauce placed over low heat while you prepare the rest of your casserole.
Preheat the oven to 375 degrees F and spray a large 9x13 inch baking dish with a non-stick spray. Set aside.
To a large stockpot, add the potatoes. Fill the pot with just enough water that it covers the potatoes. Season with salt. Heat over high heat and bring the potatoes to a boil. Cook for 5-6 minutes until just tender, not mushy. Drain and set aside.
In a medium-sized bowl, combine the cheeses until thoroughly combined. Set aside.
To your prepared baking dish, add a layer of sliced potatoes, just so that they cover the bottom. Pour 1/3 of the cheese sauce on top and sprinkle 1/3 of the grated cheese on top of that. Repeat these steps 2 more times.
In a small bowl, combine the melted butter and both bread crumbs. Stir to combine. Sprinkle the bread crumbs on top of the potatoes. Sprinkle some black pepper on top. Spray the top with a non-stick canola oil spray.
Place in the oven and bake for 30-35 minutes or until bubbly and the top is golden brown. Remove from heat and let stand for 2-3 minutes. Sprinkle pancetta and fresh parsley on top. Serve immediately and enjoy!