Classic Rich and Silky Potato Gratin (Scalloped Potatoes) Recipe
Like many, I’ve long had a love-hate relationship with potato gratins: I’d happily devour the crispy, golden top layer but ignore the often bland, dry interior beneath. Even the most lackluster gratins boast a savory, speckled crust that’s hard to resist, but I wanted more—a gratin where every bite, from the crispy edges to the creamy center, was worth savoring. That desire drove me to test, tweak, and refine until I landed on a classic recipe that delivers on all fronts: tender, well-seasoned potatoes, a silky cream sauce, and a crunchy, cheesy crust that extends to the bottom and sides.
Why It Works
The secret to this gratin’s success lies in three key techniques, each backed by science and tested for perfection:
– Steeped aromatics: Infusing milk and cream with garlic, shallots, thyme, and peppercorns (then straining) adds deep, complex flavor without disrupting the silky texture.
– Hot milk slicing: Dropping thin russet slices directly into hot dairy retains their starch (key for thickening the sauce) and prevents oxidation (no more browned, waterlogged potatoes).
– Staged baking: Covering the gratin first ensures tender potatoes and a thickened sauce; uncovering later creates a golden, crispy crust—top, bottom, and sides.
Milk vs. Cream: The Perfect Balance
The creamy filling of a gratin comes from two processes: potatoes releasing starch (which thickens the liquid) and dairy reducing (leaving behind protein and fat that form rich, silky curds). After testing dozens of ratios, I found that a mix of 2 cups heavy cream and 1 cup whole milk strikes the ideal balance: the cream adds richness and fat for luxurious curds, while the milk contributes more protein to enhance browning and prevent the dish from feeling overly heavy.
Evaporated milk, often touted for its high protein content, didn’t yield a better result—fresh milk worked just as well, and I preferred the brightness it brought. As for eggs? Some old recipes recommend adding yolks to set the gratin, but even a small amount turned the texture brittle (like a flan) instead of soft and supple. If you want picture-perfect slices, a half yolk mixed into the dairy will do the trick—but I’d skip it for a more indulgent, creamy bite.
Boosting Flavor: Aromatics and Seasoning
A potato gratin can easily fall flat without careful seasoning, so I turned to steeping to infuse depth without cluttering the texture. Here’s how:
1. Aromatic base: Simmer cream, milk, garlic (smashed, not minced—less bitterness), shallots, fresh thyme, and whole black peppercorns until just boiling. Remove from heat, cover, and let steep for 1 hour. The result? A dairy mixture perfumed with warm, earthy flavors.
2. Strain and season: After steeping, strain out the solids (they’ve given their all) and add a pinch of freshly grated nutmeg (for warmth) and a generous dose of salt. Over-salting the dairy is key: the potatoes will absorb the flavor as they cook, ensuring every slice is well-seasoned (sprinkling salt between layers leads to uneven seasoning).
The Ideal Potato: Russets for Creaminess and Crispness
For a gratin that’s both creamy (inside) and crispy (outside), high-starch russet potatoes are non-negotiable. They’re low in moisture, so they absorb the flavorful dairy quickly, becoming tender and plump. Their high starch content is also crucial—when cooked, they release starch into the liquid, thickening the sauce into a velvety coating that binds the potatoes together.
The only downside? Russets oxidize fast (turning brown when sliced). Most recipes say to soak them in water, but that washes away valuable starch. My fix? Slice the potatoes directly into the hot, infused milk. The heat stops oxidation (no more browned potatoes) and keeps all the starch in the dish—where it belongs.
To Cheese or Not to Cheese? A Middle Ground
Opinions on cheese in potato gratin are divided: purists say it’s unnecessary (the dairy should provide all the creaminess and flavor), while others swear by it. I fall somewhere in the middle: a small amount of cheese adds brightness, nuttiness, and a crispy crust—without making the dish greasy.
Here’s my approach: mix grated Parmigiano-Reggiano (salty, tangy) and Gruyère (nutty, melty) and sprinkle a light layer between potato slices. Skip the cheese on the top layer for the first bake (it’ll burn), then add a final sprinkle before uncovering. The result? A crunchy, cheesy crust that wraps around the entire gratin—no more neglected bottom layers.
Putting It All Together: The Step-by-Step
Now that you know the “why,” here’s the “how” to make this classic gratin:
1. Infuse the dairy: Simmer cream, milk, and aromatics; steep for 1 hour; strain.
2. Slice and soak: Use a mandoline to slice russets thin (1/16-inch) directly into the hot dairy—this retains starch and prevents browning.
3. Layer and season: Grease a baking dish, then alternate potato slices and cheese (save some for the top). Pour the dairy over the layers.
4. Bake in stages: Cover the dish first to tenderize potatoes and thicken the sauce; uncover later to crisp the crust.
Let the gratin rest for 30 minutes before slicing—this allows the sauce to set and the crust to crisp up even more.
Recipe Details
Prep time: 10 minutesCook time: 90 minutesActive time: 30 minutesSteeping/resting time: 90 minutesTotal time: 3 hours 10 minutesServes: 8
Ingredients
2 cups (480 ml) heavy cream
1 cup (240 ml) whole milk
2 medium garlic cloves (8 g), smashed
2 small shallots (110 g), quartered
1/8 teaspoon freshly grated nutmeg
6 sprigs fresh thyme
2 teaspoons (6 g) whole black peppercorns
1 1/2 teaspoons (7 g) Diamond Crystal kosher salt (use 3/4 teaspoon table salt)
3 medium russet potatoes (800 g), peeled
2 ounces (60 g) grated Parmigiano-Reggiano cheese (about 1/2 cup)
4 ounces (120 g) grated Gruyère cheese (about 1 1/2 cups)
1 tablespoon (15 g) unsalted butter, softened
Directions
Infuse the dairy: In a small saucepan, combine cream, milk, garlic, shallots, nutmeg, thyme, peppercorns, and salt. Bring to a boil over medium heat, then remove from heat, cover, and let steep for 1 hour.
Strain and reheat: Return the mixture to a boil, then strain into a large heatproof bowl (press gently on the solids to extract all flavor).
Slice potatoes: Using a mandoline, slice the peeled russets crosswise into 1/16-inch (1.5 mm) thick slices—drop them directly into the hot dairy as you go. Stir to coat.
Prep and layer: Preheat the oven to 350°F (177°C). Grease a 2-quart baking dish with butter. In a small bowl, mix the Parmigiano-Reggiano and Gruyère.
Layer 1/4 of the potato slices in the dish, then sprinkle with 1/3 cup of the cheese mixture. Repeat until all potatoes are used (about 4 layers), leaving the top layer cheese-free.
Pour any remaining dairy over the layers.
Bake: Cover the dish with aluminum foil and bake for 1 hour. Remove the foil, sprinkle the remaining cheese on top, and bake uncovered for 15-20 minutes (until the potatoes are tender, the sauce is thick, and the crust is golden).
Rest and serve: Let the gratin rest for 30 minutes before slicing. Serve warm.
Nutrition Facts (Per Serving)
Nutrient
Amount
% Daily Value*
Calories
442
—
Total Fat
31g
40%
Saturated Fat
20g
98%
Cholesterol
98mg
33%
Sodium
627mg
27%
Total Carbohydrate
29g
10%
Dietary Fiber
3g
11%
Protein
12g
—
Vitamin C
10mg
51%
Calcium
320mg
25%
Iron
1mg
8%
Potassium
735mg
16%
*Percent Daily Values (DV) are based on a 2,000-calorie diet.
