Wash potato slices then dry them completely and set to the side.

Add salt, pepper, paprika, onion powder and garlic powder to a large bowl and whisk together until combined.

Preheat oven 400. Grease a large casserole dish with a cover.

In a medium pot over medium heat, melt butter. Whisk in flour into melted butter until completely combined.

Whisk in half and half and a ½ cup of monterey jack cheese and a ½ cup colby cheddar cheese until completely combined then remove from heat and set aside.

Add dried potato slices to the seasoning bowl and toss evenly covering all the slices with seasoning.

Add half of the potatoes in one layer to the pan then pour half of the cheese sauce over them and spread it out covering the layer. Repeat with the final layer of potatoes and pour remaining cheese sauce on top making sure all of the potatoes are COMPLETELY COVERED. Sprinkle the top with remaining cheese.

Add all of the potatoes and then pour the cheese sauce on top and sprinkle with cheese. For baking vertically, you MUST DOUBLE THE SAUCE AND SEASONING AMOUNT BECAUSE THERE ARE MORE POTATOES AND THEY ARE HIGHER IN THE DISH. When stacking the potatoes, still lay them down on a diagonal so they still lay down a bit to get the full sauce. SEE NOTES BELOW FOR THE FULL INFO ON HOW TO DO THIS.

Bake covered in the oven for 30 minutes then remove the cover and bake for an additional 30-50 minutes (depending on how thick your slices are) or until cheese is melted and bubbly and potatoes are completely tender.

Remove from oven and allow to cool for 10-15 minutes then serve.