Preheat the oven to 375°F and spray a 9X11 baking casserole dish with non-stick cooking spray. Set aside.

In a medium saucepan on medium heat, melt the butter. Once the butter has melted and it begins to bubble, whisk in the flour. It will begin to look clumpy. Slowly add in the whole milk and stir. Add the half and half and stir. The milk sauce will thicken.

Once the milk mixture begins to thicken add the garlic powder, onion powder, cayenne pepper, black pepper, and salt. Stir in spices. As the milk continues to steam, add ½ cup of the white cheddar cheese and stir until the cheese dissolves. Next, add the chopped chives and stir. Remove from heat.

Add one layer of the potato slices to the baking dish and sprinkle with a little salt. Pour cheese sauce on top of the first layer of potatoes and sprinkle with an additional ½ cup of grated white cheddar cheese.

Add another layer of thinly sliced potatoes on top of the milk mixture, sprinkle with a little sauce and pour the rest of the cheese mixture on top of the potatoes. Sprinkle the remaining cheese on top of the top layer of potatoes and also sprinkle with chopped chives. Bake the potatoes in the middle-low rack for 40-45 minutes, uncovered. Remove from the oven and allow the potatoes to cool. The potatoes should be fork-tender. Cover in aluminum foil until ready to serve.