Preheat your oven to 425°F. While it heats, peel and slice the potatoes into 1/8-inch thick rounds—I find using a mandoline here saves time and ensures even cooking. Mince the shallot finely. In one small bowl, combine the thyme, salt, and pepper. In another bowl, combine the mozzarella, asiago, and gruyere cheeses. Have the parmesan, nutmeg, and cream measured and ready nearby.

Melt 1.5 tablespoons of butter in a 10-12 inch oven-safe skillet over medium heat. Create the first layer with half of the sliced potatoes, slightly overlapping them for even cooking. Sprinkle two-thirds of the shallot-thyme mixture over the potatoes, then distribute half of the cheese blend from Step 1 evenly across. Layer the remaining potatoes on top, followed by the last of the shallot-thyme mixture.

Pour the cream evenly over the layered potatoes and sprinkle the freshly grated nutmeg and garlic powder across the surface. Bring to a gentle simmer over medium heat and cook for about 5 minutes—this helps the potatoes begin to soften and allows the cream to infuse with the seasonings. I like to use freshly grated nutmeg here because it releases its aromatic oils and tastes far superior to pre-ground.

Remove the skillet from heat and dot the top with the remaining 1.5 tablespoons of butter, cut into small pieces. Scatter the remaining cheese blend from Step 1 over the surface, then finish with the parmesan. Transfer the skillet to the preheated 425°F oven and bake for 25-30 minutes, until the top is golden brown and the cream is bubbling around the edges.

Remove the skillet from the oven and let the scalloped potatoes rest for 5 minutes before serving. This resting period allows the cream sauce to set slightly, making it easier to serve and ensuring each spoonful stays creamy. I find this brief rest makes a noticeable difference in texture and presentation at the table.