This oven baked 4-ingredient spring onion potato bake is one of those cozy, hand-me-down recipes I learned from my grandmother that somehow feels fancy without any effort. It’s just thinly sliced potatoes and a creamy sauce, baked until bubbly and golden around the edges, then showered with fresh spring onions so you get that rich-creamy meets bright-fresh combo in every bite. With only four ingredients and a simple glass casserole dish, it’s the kind of weeknight-friendly side that still feels special enough for Sunday dinner or holidays.
This potato bake is rich and comforting, so it pairs really well with simple mains like roasted chicken, grilled pork chops, seared steak, or baked salmon. I also love serving it with a big green salad dressed with something tangy to balance the creaminess, or alongside roasted vegetables like carrots, green beans, or Brussels sprouts. If you’re hosting, you can set the glass casserole dish right on the table so everyone can scoop out those creamy slices and bright green spring onions—it looks especially inviting next to a platter of sliced roast meat or a simple veggie-forward main.
4-Ingredient Spring Onion Potato BakeServings: 4
Ingredients
2 pounds russet or Yukon Gold potatoes, thinly sliced
2 cups heavy cream
1 1/2 teaspoons kosher salt (plus more to taste)
1 large bunch spring onions (about 1 cup sliced, white and green parts)
Directions
Preheat your oven to 375°F (190°C). Lightly grease a medium glass casserole dish (about 8x8 inches or similar) with a bit of cream or neutral oil so the potatoes don’t stick.
Rinse and pat dry the spring onions. Trim off the root ends and any wilted greens, then thinly slice both the white and green parts. Set aside, keeping a small handful of the green tops separate for sprinkling on at the end.
Peel the potatoes if you like (my grandmother always did), or leave the skins on for a more rustic feel. Slice the potatoes as thinly and evenly as you can, about 1/8 inch thick. A sharp knife works fine; a mandoline makes this even faster if you have one.
In a large bowl, add the sliced potatoes, most of the sliced spring onions (reserve that small handful of green tops), the heavy cream, and the kosher salt. Toss gently with clean hands or a large spoon until the potatoes are well coated and the spring onions are evenly distributed.
Pour the potato mixture into the prepared glass casserole dish, spreading it out into an even layer. Gently press down with the back of a spoon to settle the slices and make sure the cream is distributed throughout. The cream should just about come up to the top layer of potatoes; if it looks a bit dry, you can splash in another 1/4 cup of cream.
Cover the dish tightly with foil and bake in the preheated oven for 35 to 40 minutes, until the potatoes are mostly tender when pierced with the tip of a knife and the cream is starting to bubble around the edges.
Remove the foil and continue baking for another 20 to 25 minutes, or until the top is lightly golden, the cream is thickened into a rich sauce, and the potatoes are completely tender all the way through. If the top browns too quickly, you can loosely tent with foil again for the last 5 to 10 minutes.
Take the dish out of the oven and let it rest for at least 10 minutes. This short rest helps the creamy sauce thicken slightly so the slices hold together better when you scoop them out.
Right before serving, sprinkle the reserved sliced spring onion greens evenly over the top. Serve the bake straight from the glass casserole dish, making sure each scoop includes some of the creamy sauce and plenty of those vibrant green onions.
Variations & Tips
To keep the spirit of the four-ingredient recipe, I like to treat extras as optional add-ons rather than part of the base. For a little extra richness, you can whisk in 1/4 cup grated Parmesan or sharp cheddar into the cream before tossing with the potatoes. A small pinch of black pepper or garlic powder also plays nicely if you don’t mind bending the four-ingredient rule. If you prefer a lighter version, you can swap half of the heavy cream for whole milk, though the sauce will be a bit looser; bake covered a little longer so the potatoes still get tender. For dairy-free, use a rich, unsweetened plant-based cream (like oat or cashew) and watch closely near the end so it doesn’t separate—pull it from the oven as soon as the potatoes are tender and the sauce is just bubbling. You can also trade the spring onions for thinly sliced leeks or chives if that’s what you have on hand. Food safety tips: Keep the cream refrigerated until you’re ready to assemble, and don’t leave the baked dish at room temperature for more than 2 hours; refrigerate leftovers in a covered container and reheat thoroughly in the oven or microwave until steaming hot before serving. If using a mandoline for slicing, always use the safety guard or a cut-resistant glove to protect your fingers.
