Preheat the oven to 425° F.
Place the potatoes in a large bowl and toss with the salt, garlic powder, and pepper to coat.
Melt 1 tablespoon of the butter in a large skillet over medium-high heat.
Add half of the potatoes, and toss with the butter.
Use a fork to spread the potatoes into a single layer.
Sprinkle with half of the cheddar and gruyere cheese, and then arrange the remaining potatoes on top.
Reduce to medium heat
Pour half and half over the potatoes and add the bay leaves.
Cook for 5 minutes.
Spray a shallow dish with cooking spray and slide the potatoes and cream into it.
Arrange with a fork.
Cut the remaining 1 tablespoon of the butter into small cubes and scatter on top of the potatoes.
Top with the remaining shredded cheese and parmesan.
Bake for 30 minutes, until golden brown. (Tent with foil in the last 10 minutes to prevent browning if necessary.)
Discard the bay leaves and let rest for 5 minutes before serving.