Eggs and Potassium: Spinach Potato Skillet

This spinach potato egg skillet combines tender diced potatoes, leafy spinach, and softly set eggs in one ovenproof pan. It makes a savory breakfast, brunch, or simple supper, and the potatoes and spinach bring potassium-containing ingredients to a dish centered on eggs.

Ingredients

2 tablespoons (30 ml) olive oil, divided
12 ounces (340 g) Yukon Gold or red potatoes, scrubbed and cut into ½-inch (1.3 cm) cubes
¼ cup (60 ml) water
½ medium yellow onion, finely diced, about ½ cup (75 g)
3 cups (90 g) baby spinach, loosely packed
8 large eggs (about 400 g without shells)
¼ cup (60 ml) whole milk or unsweetened oat milk
½ teaspoon (2.5 g) kosher salt, plus more to taste
¼ teaspoon (0.5 g) freshly ground black pepper
¼ teaspoon (0.5 g) smoked paprika
½ cup (56 g) shredded sharp cheddar, optional
1 tablespoon (4 g) chopped fresh parsley, optional, for serving

Instructions

Set a rack in the center of the oven and heat it to 400°F (205°C). While it heats, scrub and dice the potatoes, chop the onion, and measure the remaining ingredients. If your skillet handle is not oven-safe, check the manufacturer’s instructions before using it in the oven; otherwise, transfer the mixture to a greased baking dish before adding the eggs.
Set a 10-inch (25 cm) ovenproof skillet over medium heat and add 1 tablespoon (15 ml) of the olive oil. Add the potatoes and water, then cover the pan. Cook for 12 to 14 minutes, stirring once or twice, until a knife can pierce a potato cube with slight resistance. Keep the heat moderate so the water does not evaporate before the potatoes soften. If the pan becomes dry and the potatoes are still firm, add 1 tablespoon (15 ml) water and cover again for a few minutes.
Remove the lid and let any remaining water evaporate. Add the remaining 1 tablespoon (15 ml) oil and the onion. Cook uncovered for 4 minutes, stirring occasionally, until the onion softens and the edges of the potatoes begin to turn golden. If the potatoes are sticking, lower the heat rather than scraping hard; browned bits are welcome, but burnt ones can make the finished eggs taste bitter.
Add the spinach in two handfuls, stirring after each addition. Cook for about 2 minutes, just until the leaves have wilted and any liquid in the pan has mostly evaporated. Spread the potato mixture evenly across the skillet. This brief cooking step keeps excess moisture from pooling beneath the eggs and helps the frittata set evenly.
In a medium bowl, whisk the eggs with the milk, salt, pepper, and smoked paprika until the whites and yolks are blended. Pour the mixture evenly over the vegetables. Sprinkle the cheddar on top if using. Do not stir once the eggs are in the pan; leaving the layers undisturbed helps the skillet hold together when sliced.
Transfer the skillet to the oven and bake for about 14 minutes. Check the center with a food thermometer; egg dishes should reach the USDA FSIS safe minimum internal temperature of 160°F (71°C). If the center has not reached that temperature, return the pan to the oven and check again after 2 minutes. The center should look set rather than liquid, though a small amount of movement as the pan is nudged is normal. Use oven mitts when handling the skillet, including after it has been out of the oven for a few minutes.
Let the frittata stand for 3 minutes, then cut it into four wedges. Scatter with parsley if desired and serve warm. The brief standing time makes the slices easier to lift; it is included within the recipe’s total cooking time.

Tips

Cut the potatoes evenly. Pieces close to ½ inch (1.3 cm) cook at a similar rate. Larger cubes may still be firm when the egg mixture is ready, while very small pieces can turn mushy. If you are using a waxy red potato, leave the skin on for texture; peel a russet if you prefer a softer, fluffier bite.
Control moisture before adding eggs. Spinach releases water as it cooks, and wet vegetables can leave the center loose. Let visible liquid evaporate in the skillet before pouring in the eggs. Frozen spinach also works: thaw it completely, squeeze it very dry, and use about ½ cup (90 g) after squeezing.
Use a reliable ovenproof pan. A well-seasoned cast-iron skillet or an oven-safe stainless-steel skillet works well. A nonstick pan is suitable only if its handle and coating are rated for a 400°F (205°C) oven. When in doubt, cook the vegetables in a regular skillet and move them to a greased 8-inch (20 cm) square baking dish before adding the eggs; the bake may take a few minutes longer, so check the center temperature.
Season with the cheese in mind. Cheddar adds salt, so taste the vegetables before adding extra salt and keep the listed amount as a starting point. For a saltier cheese such as feta, reduce the kosher salt slightly. For a dairy-free version, leave out the cheese and use an unsweetened non-dairy milk.

Serving Suggestions

Serve a wedge on its own for breakfast or brunch, or pair it with toast, warm tortillas, or a small pile of roasted tomatoes. For a fuller lunch, add a crisp green salad dressed with lemon juice and olive oil; a simple vinaigrette gives the soft eggs and potatoes a bright contrast. Sliced avocado, chopped scallions, or a spoonful of plain yogurt can be offered at the table so everyone can finish a portion to taste.

The recipe is also easy to serve family-style: place the skillet on a heat-safe trivet and let diners take wedges, using a broad spatula to support the potatoes. Add fruit or a bowl of berries for a breakfast spread, or serve with soup for an easy evening meal. If preparing other dishes at the same time, keep the frittata warm only briefly while covered loosely; for longer waits, refrigerate it promptly rather than leaving cooked eggs at room temperature.

Variations

Use other greens: Replace the baby spinach with 2 cups (60 g) chopped kale or Swiss chard. Remove tough kale stems and cook the leaves for several minutes longer than spinach, until tender, before adding the eggs. Chard stems can be finely diced and sautéed with the onion; they add a little crunch and may need an extra minute or two.

Add another vegetable: Sauté ½ cup (75 g) diced red bell pepper with the onion, or use ½ cup (75 g) halved cherry tomatoes. Cook watery vegetables until their released liquid has mostly evaporated. Mushrooms are another option: brown 1 cup (70 g) sliced mushrooms before adding spinach, since they release moisture as they cook.

Change the cheese or seasoning: Substitute crumbled feta, Monterey Jack, or grated Parmesan for cheddar. Feta gives the skillet a tangier, saltier flavor, while Monterey Jack is mild and melts smoothly. For a little warmth, add ⅛ teaspoon (0.3 g) red pepper flakes with the paprika. Fresh dill or chives can replace parsley, depending on the flavors you like.

Make it without dairy: Use unsweetened oat or soy milk and omit the cheese, or choose a dairy-free shredded cheese. The milk adds a tender texture but is not essential, so you can use ¼ cup (60 ml) water instead. Avoid flavored or sweetened plant milk, which can make a savory egg dish taste unexpectedly sweet.

Try a different potato: Yukon Gold potatoes stay creamy, and red potatoes hold their shape. Russets also work, though they soften more readily and can break apart when stirred. Keep the pieces evenly sized and handle them gently after they become tender. Sweet potato cubes can be used, but their sweetness changes the flavor; check them for tenderness during the covered cooking step because they may soften sooner.

Storage and Reheating

Refrigerate leftover frittata within 2 hours of cooking. Once it has cooled enough to handle, place wedges in a shallow airtight container and refrigerate for 3 to 4 days. For easier reheating, store portions separately and keep fresh toppings, such as parsley or avocado, apart until serving. Do not leave the skillet on the counter for an extended brunch; move leftovers into the refrigerator promptly.

Reheat individual portions in the microwave in 30-second intervals, turning or checking the slice between intervals to warm it evenly. For a larger portion, cover it loosely in an oven-safe dish and warm at 325°F (165°C) until hot throughout. Leftovers should reach 165°F (74°C) when reheated, as measured with a food thermometer. Avoid repeated reheating and cooling; warm only the amount you plan to eat.

You can freeze portions for up to 2 months for best texture. Wrap each cooled slice well or place it in a freezer-safe container. Thaw overnight in the refrigerator, then reheat to 165°F (74°C). The eggs may be slightly less tender after freezing, and the potatoes can soften, but the slices remain convenient for a quick meal. Do not freeze the frittata while it is still warm, since that can cause condensation and affect its texture.

Frequently Asked Questions

Do eggs contain potassium? Yes. A large egg contains roughly 69 mg of potassium in standard food-composition references, though exact values vary with egg size and the source of the data. This recipe also includes potatoes and spinach, and the quantities here are intended for a flavorful skillet rather than a specific nutrition target.

Can I make this recipe without potatoes? Yes, though the skillet will be less substantial and may cook faster. Replace the potatoes with about 1½ cups (225 g) of chopped vegetables that have been cooked until tender and had their excess moisture removed. If you simply leave the potatoes out, reduce the skillet cooking time and begin checking the egg center temperature a few minutes earlier.

Can I prepare the ingredients ahead? You can dice the onion and potatoes up to a day ahead and refrigerate them in separate covered containers. For the best texture, cook the vegetables and eggs shortly before serving. You can also cook the entire frittata ahead, chill it within 2 hours, and reheat portions later; avoid partially cooking the eggs in advance and holding them for later finishing.

How can I tell when the center is done? The most reliable check is a food thermometer inserted into the center of the egg mixture, away from the skillet surface. It should read 160°F (71°C), the USDA FSIS safe minimum for egg dishes. A set-looking top alone is not a dependable safety check, especially if the center is thick or the pan has been crowded with vegetables.

Can I use frozen spinach? Yes. Thaw it first and squeeze out as much liquid as possible, then measure about ½ cup (90 g) of squeezed spinach in place of the fresh leaves. Stir it into the cooked potatoes and onion just long enough to heat through and let any remaining moisture evaporate. Adding it frozen or still wet can make the eggs watery and extend the baking time.

What if I do not have an ovenproof skillet? Cook the potatoes, onion, and spinach in your usual skillet, then transfer the vegetables to a greased 8-inch (20 cm) square baking dish. Pour the whisked egg mixture over them, add cheese if using, and bake at the same temperature. Begin checking after about 14 minutes, but expect the time to vary with the dish’s material and depth; use the thermometer to confirm 160°F (71°C) at the center.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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