My grandmother made this creamy side dish for decades, and it melts in your mouth. It only takes 3 ingredients.

This oven baked 3-ingredients Irish champ bake is my cozy, no-fuss version of the creamy potato side my grandmother made for every holiday. Traditional Irish champ is just mashed potatoes with scallions and plenty of butter, and this baked version turns it into a fluffy, golden casserole with a little pool of melted butter in the center—exactly how she served it in her old white casserole dish. It’s the kind of recipe you make when you’re juggling work, kids, and a busy week, but still want something that feels like it came straight from grandma’s table.

Serve this champ bake alongside roasted chicken, baked ham, or a simple skillet steak. It’s also perfect with pan-seared sausages or meatloaf to soak up all the juices. Add a green vegetable like steamed green beans, roasted Brussels sprouts, or a simple side salad for balance. If you’re doing a holiday spread, tuck this casserole right next to the stuffing and gravy—it holds well on a warm setting and stays creamy for second helpings.

Servings: 6

3 pounds russet potatoes, peeled and cut into chunks

Preheat your oven to 375°F (190°C). Lightly grease a medium vintage-style or standard 2-quart casserole dish with a bit of the butter so the potatoes don’t stick.

Place the peeled, chunked potatoes in a large pot and cover with cold water by about 1 inch. Add a generous pinch of salt if you like, then bring to a boil over high heat.

Reduce the heat to a gentle boil and cook the potatoes for 15–20 minutes, or until they are very tender and easily pierced with a fork.

Drain the potatoes well and return them to the hot pot. Let them sit for 1–2 minutes so excess moisture can steam off; this keeps the mash fluffy instead of watery.

Add 1/2 cup of the salted butter to the hot potatoes. Mash until smooth and creamy, taking a minute to really work out any lumps. Taste and add a pinch of salt if needed, depending on how salty your butter is.

Stir in the sliced green onions until they’re evenly distributed throughout the mashed potatoes. The heat from the potatoes will soften them slightly while keeping their fresh flavor.

Spoon the mashed potato mixture into the prepared casserole dish, smoothing the top with the back of a spoon. Use the spoon to make a shallow well or pool in the center of the potatoes.

Cut the remaining 1/2 cup salted butter into pieces. Nestle several pieces into the well in the center and dot the rest around the top of the potatoes so they melt and create golden spots as they bake.

Bake uncovered for 20–25 minutes, or until the top is lightly golden around the edges and the butter has melted into a glossy pool in the center. The potatoes should look fluffy and slightly puffed.

Remove from the oven and let the champ bake sit for about 5 minutes. If you like, sprinkle a few extra sliced green onions over the top for color. Serve warm straight from the casserole dish, making sure everyone gets some of the melted butter from the center with their scoop.

To make this even creamier, you can swap a few tablespoons of the butter for heavy cream or whole milk, but keep in mind that technically adds a fourth ingredient. For a slightly lighter version, use 1/2 cup butter total and add a splash of the potato cooking water while mashing to loosen things up. If you prefer a bit of texture, mash the potatoes by hand and leave a few small chunks instead of going completely smooth. For a sharper onion flavor, reserve a small handful of the green onions and fold them in right before transferring to the baking dish so they stay a bit crisper. You can also prep this dish ahead: mash the potatoes and stir in the butter and onions, spread into the casserole, cover, and refrigerate for up to 24 hours. When ready to bake, dot with the remaining butter and bake an extra 5–10 minutes, until heated through and golden. Leftovers reheat well in the oven, covered with foil, with a small pat of butter on top to bring back that silky texture.