This Caramelized Onion and Gruyère Potato Gratin is the definition of a luxurious steakhouse side dish. Inspired by the rich, indulgent flavors you’d expect at Ruth’s Chris, it features tender layers of potatoes baked in a silky cream sauce, balanced by sweet caramelized onions and nutty, melty Gruyère cheese. What sets this gratin apart is the slow-cooked onions. Taking the time to caramelize them properly adds deep sweetness and complexity that elevates the entire dish. Combined with creamy Yukon Gold potatoes, the result is a perfectly balanced bite that is both comforting and refined. The cheese blend plays a crucial role here. Gruyère brings richness and depth, while Parmesan adds a subtle sharpness and a beautifully golden top. Together, they create a gratin that is irresistibly creamy inside with a lightly crisp, bubbling surface. Ideal for holiday tables, dinner parties, or an elevated weeknight meal, this potato gratin pairs beautifully with steak, roast chicken, or pork. It’s a timeless side dish that feels indulgent, elegant, and unforgettable.