Peel and thinly slice the Yukon Gold potatoes into ⅛-inch rounds. Preheat your oven to 375°F (190°C) while you work. Arrange the potatoes in a bowl of cold water to prevent browning.

In a saucepan, melt 3 tablespoons of butter over medium heat. Add garlic powder and onion powder, cooking for about 1 minute until fragrant. Gradually whisk in heavy cream and whole milk, simmering for 3-4 minutes. Stir in cheddar and Gruyère cheese until smooth; season with salt and cracked black pepper.

Grease a baking dish with butter. Layer the sliced potatoes and pour cheese sauce between each layer. Finish with a layer of cheese sauce on top and sprinkle fresh thyme leaves over it.

Cover with foil and bake for 35 minutes. Remove foil and bake for another 20-25 minutes until golden and fork-tender.

Heat a cast-iron skillet over high heat. Season ribeye steaks with salt and cracked black pepper. Add 1 tablespoon of butter and sear each steak for 3-4 minutes per side. Let rest for 5 minutes.

Plate the ribeye steak alongside a generous scoop of cheesy scalloped potatoes and garnish with fresh thyme sprigs.