This healthy potato casserole pairs tender potatoes with a creamy, savory sauce, vegetables, and a crisp golden topping. Greek yogurt and milk keep it satisfying without relying on heavy cream, while a little sharp cheddar adds plenty of flavor.
Ingredients
- 2 pounds Yukon Gold potatoes, scrubbed and cut into ½-inch cubes
- 1 tablespoon olive oil, plus a little for greasing the dish
- 1 medium yellow onion, finely chopped
- 2 cups small broccoli florets, cut into bite-size pieces
- 2 cloves garlic, minced
- 2 tablespoons all-purpose flour
- 1 cup low-sodium chicken or vegetable broth
- ¾ cup 2% milk
- ¾ cup plain, unsweetened Greek yogurt
- 1 teaspoon Dijon mustard
- ½ teaspoon kosher salt, plus more for the potato water
- ¼ teaspoon black pepper
- ½ teaspoon smoked paprika
- 1 cup shredded sharp cheddar, divided
- ⅓ cup whole-wheat breadcrumbs
- 1 tablespoon chopped fresh chives, for serving (optional)
Instructions
- Heat the oven and prepare the potatoes. Set a rack in the center of the oven and heat it to 400°F (200°C). Lightly oil a 9-by-13-inch baking dish. Put the potato cubes in a large pot, cover with cold water by about an inch, and add a generous pinch of salt. Bring to a boil, then simmer for 8–10 minutes, until a knife enters the potatoes with slight resistance. They should not be falling apart; they will finish cooking in the oven.
- Drain and steam-dry. Drain the potatoes well in a colander and leave them there for a few minutes so excess moisture evaporates. This helps prevent a watery casserole. Meanwhile, steam or blanch the broccoli for 2–3 minutes, just until bright green and barely tender, then drain and set aside.
- Cook the aromatics. Warm the olive oil in a saucepan over medium heat. Add the onion and cook for 4–5 minutes, stirring occasionally, until soft and translucent. Stir in the garlic and cook for about 30 seconds, just until fragrant.
- Make the lighter sauce. Sprinkle the flour over the onion mixture and stir for 1 minute. Slowly pour in the broth while whisking to avoid lumps, then whisk in the milk. Bring the sauce to a gentle simmer and cook for 2–3 minutes, stirring, until it thickens enough to coat a spoon. Remove the pan from the heat. Let it cool for 2 minutes, then whisk in the Greek yogurt, Dijon, salt, pepper, and smoked paprika. Taking the sauce off the heat before adding yogurt helps keep it smooth.
- Assemble the casserole. Add the potatoes and broccoli to the prepared dish. Pour the sauce over them and gently toss until evenly coated. Sprinkle ¾ cup of the cheddar over the top, followed by the breadcrumbs and the remaining ¼ cup cheddar.
- Bake until golden and hot. Bake uncovered for 25–30 minutes, until the edges bubble and the top is golden. For food safety, the center should reach 165°F (74°C); check with an instant-read thermometer, avoiding contact with the dish. If the top browns before the center is hot, loosely cover it with foil and continue baking.
- Rest and serve. Let the casserole stand for 5–10 minutes so the sauce settles and portions hold together. Scatter chives over the top, if using, and serve warm.
Tips
- Keep the potatoes in pieces. Cut them evenly and stop boiling while they are still slightly firm. Overcooked potatoes can break apart when tossed with the sauce.
- Use room-temperature yogurt if possible. Cold yogurt is more likely to seize when it meets warm sauce. Always remove the pan from the heat before stirring it in, and avoid boiling the sauce afterward.
- Choose a suitable substitute. Plain regular yogurt can replace Greek yogurt, but the sauce will be thinner. For a gluten-free casserole, use a measure-for-measure gluten-free flour blend and gluten-free breadcrumbs.
- Check seasoning before baking. Broth and cheese vary in saltiness. Taste the sauce before combining it with the potatoes and adjust the salt and pepper as needed.
Serving Suggestions
Serve this casserole as a hearty vegetarian main with a crisp green salad dressed in vinaigrette, or alongside roasted green beans, carrots, or Brussels sprouts. It also works as a side dish with roasted chicken, baked fish, or beans. Since the casserole contains potatoes, cheese, and vegetables, a fresh, acidic side helps balance its creamy texture.
Variations
For a different vegetable combination, replace the broccoli with 1½ cups chopped cauliflower, sautéed mushrooms, or thawed frozen peas. If using frozen vegetables, thaw and drain them well first to avoid excess water. For extra protein, fold in 1½ cups of cooked, shredded chicken or drained white beans before baking. You can swap the cheddar for Gruyère or Monterey Jack, though milder cheese will give a less pronounced flavor. Add ½ teaspoon dried thyme or a pinch of cayenne to the sauce if you like a more herbaceous or spicy casserole.
Storage and Reheating
Let leftovers cool briefly, then refrigerate them in a covered container within 2 hours of cooking (within 1 hour if the room temperature is above 90°F/32°C). Keep refrigerated at 40°F (4°C) or below and use within 3–4 days. Reheat individual portions in the microwave, covered loosely, until steaming hot throughout; stir or rotate halfway through if needed. For larger portions, cover the dish with foil and heat in a 350°F (175°C) oven until the center reaches 165°F (74°C), usually 20–30 minutes, depending on portion size. Add a splash of milk or broth if the sauce has thickened. Refrigerate leftovers promptly again, and avoid repeated cycles of reheating and cooling.
Frequently Asked Questions
Can I make this casserole ahead?
Yes. You can boil and drain the potatoes, prepare the sauce, and cook the broccoli up to one day ahead. Refrigerate the components separately, then assemble and bake shortly before serving. If you assemble the whole dish in advance, keep it covered and refrigerated, and allow extra baking time because it will be cold.
Can I use a different kind of potato?
Yukon Gold potatoes have a creamy texture and hold their shape well, but red potatoes work similarly. Russets are starchier and more likely to crumble, so handle them gently and stop boiling as soon as they are just tender.
Can I freeze healthy potato casserole?
You can freeze it, but the potatoes and yogurt-based sauce may become softer or slightly grainy after thawing. For best quality, cool the casserole, portion it into airtight freezer-safe containers, and freeze for up to 2 months. Thaw overnight in the refrigerator and reheat to 165°F (74°C). Freeze only food that has not been left at room temperature for more than 2 hours.
How do I know when the potatoes are cooked?
Before baking, a knife should slide into a potato cube with slight resistance. After baking, the potatoes should be tender and the casserole center should reach 165°F (74°C). Checking both texture and temperature helps avoid undercooked potatoes or an overbaked, dry top.
Why did my sauce turn watery?
Common causes are wet vegetables, potatoes that were not drained and steam-dried, or a sauce that was too thin before assembly. Drain broccoli and potatoes thoroughly, simmer the flour-and-liquid mixture until it coats a spoon, and avoid adding frozen vegetables without thawing and draining them first.
Can I make it without breadcrumbs?
Yes. Leave them off for a softer cheese topping, or use ⅓ cup finely chopped nuts or gluten-free breadcrumbs for crunch. Keep the baking temperature and doneness check the same, watching the top so it does not brown too quickly.