I love a recipe that comforts without fuss. Spinach Mashed Potatoes is exactly that: familiar mashed potatoes brightened with tender, savory spinach and a little tang from sour cream. It’s a humble side that lifts weeknight dinners and plays well next to roast chicken or a simple pan-seared fish.

This version keeps things straightforward—no fancy equipment, no odd ingredients—and focuses on technique so your potatoes stay fluffy and the spinach blends through without becoming watery. Read through the ingredients and method once, then get cooking; it moves quickly once the potatoes are on the stove.

What You’ll Gather

Ingredients

10 oz frozen chopped spinach, thawed, drained — squeeze out excess water so the potatoes don’t become runny; this is the primary green and flavor booster.
6 potatoes, peeled and chopped into 1″ cubes — Yukon Gold or russet both work; uniform cubes cook evenly.
1/4 cup butter — adds richness and helps create a smooth mouthfeel.
1 cup sour cream — gives tang and creaminess; fold in at the end for moisture and flavor balance.
1 teaspoon onion powder — concentrated onion flavor without texture.
1 teaspoon salt — seasons the potatoes; adjust to taste.
1 teaspoon dill weed — a light herbal note that complements spinach.
1/4 teaspoon black pepper — for a subtle warmth.
1 cup shredded mozzarella cheese — melts into a mild, gooey topping.

Method: Spinach Mashed Potatoes

Preheat the oven to 350°F and grease a casserole dish with nonstick cooking spray. Set the dish aside so it’s ready when you finish the potatoes.
Place the peeled, 1″-cubed potatoes in a large stockpot. Add cold water to cover the potatoes by about 1 inch.
Set the pot over medium-high heat and bring to a boil. Once boiling, reduce slightly so the water maintains a steady boil; cook 10–15 minutes, or until a fork slides easily into a cube with no resistance.
Drain the potatoes thoroughly in a colander, then return them to the pot or place in a mixing bowl for mashing.
Add the 1/4 cup butter to the hot potatoes and mash until mostly smooth—use a potato masher or ricer depending on your texture preference. Work quickly so the potatoes stay warm and absorb the butter.
Drain any remaining liquid from the thawed spinach by squeezing it in a clean towel or pressing in a fine-mesh sieve. Add the drained spinach to the mashed potatoes.
Add the 1 cup sour cream, 1 teaspoon onion powder, 1 teaspoon salt, 1 teaspoon dill weed, and 1/4 teaspoon black pepper to the potato-spinach mixture. Stir well, mixing until the spices and sour cream are evenly incorporated and the spinach is distributed throughout.
Spoon the spinach mashed potatoes into the prepared casserole dish and spread into an even layer. Be gentle—do not compact the potatoes; a light hand keeps them airy.
Sprinkle the 1 cup shredded mozzarella cheese evenly over the top of the potatoes.
Bake in the preheated 350°F oven for about 20 minutes, or until the center is hot and the cheese is melted and beginning to brown. Ovens vary; if your oven runs cool, add a few minutes until heated through and the top is golden.

Why It Works Every Time

The success here comes down to temperature control and moisture management. Starting the potatoes in cold water ensures even cooking; draining them thoroughly and adding butter while they’re hot lets the fat melt in for creaminess. Removing liquid from the spinach prevents a watery mash. Finally, baking briefly melts the cheese and brings everything together without drying the dish.

Swap Guide

Potatoes: Swap russet for Yukon Gold for a creamier, naturally buttery texture.
Butter: Use olive oil for a dairy-free option (texture will be slightly different).
Sour cream: Plain Greek yogurt works for tang with more protein; keep quantity the same.
Cheese: Swap mozzarella for cheddar for sharper flavor or Parmesan for a nuttier crust.
Herbs/spices: Omit dill and add a pinch of nutmeg or chopped chives for a different profile.

Toolbox for This Recipe

Large stockpot — for boiling the potatoes evenly.
Colander — to drain potatoes and squeeze out spinach liquid if needed.
Potato masher or ricer — masher for a rustic texture, ricer for silkier potatoes.
Mixing bowl — to combine potatoes, spinach, and dairy if you prefer not to mash in the pot.
Casserole dish — any 8×8 or similar-sized ovenproof dish will work.
Oven — to melt the cheese and warm through the casserole.

Troubles You Can Avoid

Watery potatoes: Don’t skip draining the spinach aggressively and drain the potatoes well. Excess water dilutes flavor and makes the mash gluey.
Gummy texture: Overworking hot potatoes—especially with a mixer—can release starch and make them gummy. Mash gently.
Cold center: If the casserole is cold in the middle after baking, either your dish was too packed (don’t compact) or the oven temperature was low—bake a few minutes longer covered loosely with foil.
Undersalted: Potatoes need more salt than you expect. Taste and adjust the 1 teaspoon if your potatoes or sour cream are low-sodium.

Make It Fit Your Plan

Weeknight dinners: Prepare the mashed potatoes up to the point of baking, cover, and refrigerate. Top with cheese and bake when ready (see Make-Ahead section for timing).
Meal prep: Portion into meal-sized containers without the cheese; when reheating, add a small sprinkle of cheese to each portion to refresh the surface.
Vegetarian main: Serve with a hearty lentil loaf or roasted mushrooms to make this a centerpiece rather than a side.

Testing Timeline

0–20 minutes: Prep and start potatoes in cold water; thaw and drain spinach.
20–35 minutes: Boil potatoes until fork-tender; drain and mash with butter.
35–45 minutes: Mix in spinach, sour cream, and seasonings; transfer to casserole and top with cheese.
45–65 minutes: Bake 20 minutes until hot and cheese is melted and slightly browned.

Make-Ahead & Storage

Make-ahead: Assemble through step 8 (spread in casserole, do not add cheese) and cover. Refrigerate up to 24 hours. When ready, add cheese and bake 20–25 minutes until hot.
Reheating: Cover leftovers with foil and reheat at 325°F until warmed through (15–25 minutes depending on portion size). For single portions, microwave covered until hot.
Storage: Keep refrigerated up to 3–4 days in an airtight container. Freeze up to 2 months—thaw in the fridge overnight and reheat; texture may be slightly softer after freezing.

Ask the Chef

Can I use fresh spinach?

Yes. Use about 8–10 cups fresh spinach, wilted in a pan and squeezed dry to match the concentrated flavor of the frozen, drained spinach.

How to make it dairy-free?

Replace butter with olive oil and sour cream with a dairy-free plain yogurt or a cashew cream. Use a dairy-free shredded cheese or skip the topping and broil briefly with a sprinkle of nutritional yeast for a savory finish.

Ready, Set, Cook

You’re set: preheat the oven to 350°F, get a pot of water on the stove, and have your spinach thawing and draining. Follow the method steps in order and trust your senses—potatoes should be tender, the mash warm and buttery, and the final bake just long enough to melt and brown the cheese. This dish is forgiving, practical, and very good company at the table. Enjoy.

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