Classic Creamy Scalloped Potatoes

Steps

1. Heat the oven to 375°F (190°C) and

   butter (how to grease and flour a pan)

   Grease and flour a pan Coat a pan with fat (and sometimes flour) so baked goods release cleanly. 1. Rub a thin layer of soft butter or shortening into every corner with a paper towel, or use baking spray.2. For cakes, add a spoonful of flour, tilt and tap the pan until it is coated.3. Turn the pan over and tap out the extra flour.4. For chocolate cakes, use cocoa instead of flour so there is no white film. Done when: Every surface, corners included, is lightly coated with no bare spots or thick clumps. How to grease and flour a baking pan: mistakes to avoid

   a 9x13-inch baking dish.
   375°F
2. Peel the potatoes and

   slice (how to slice)

   Slice Cut food into flat pieces of the same thickness. 1. Give round food a flat side to sit on.2. Hold it with your fingertips curled under.3. Cut with long strokes, pushing the knife forward and down rather than straight down.4. Move your guiding hand back the same distance each time so every slice matches. Done when: The slices are even. For meat, slicing across the grain (across the lines of muscle) gives the tenderest bite. Safety: Keep the fingertips of your guiding hand curled under, knuckles toward the blade, and set the board on a damp towel so it can't slide. Slice hot roasts on a board with a groove for the juices.How to slice evenly: mistakes to avoid

   them about 1/8 inch thick with a sharp knife or a mandoline. Don't rinse the slices; their starch helps thicken the sauce.
3. Melt the butter in a large saucepan over medium heat. Add the onion and

   cook until soft but not browned (how to sweat (vs. sauté))

   Sweat (vs. sauté) Cook vegetables gently in a little fat so they soften and turn sweet without browning. Sautéing uses higher heat to brown them. 1. Melt a spoonful of butter or warm oil over medium-low heat.2. Add the onions or other vegetables and a pinch of salt, which draws out their water.3. Stir every couple of minutes; a lid for the first few minutes helps.4. Turn the heat down if you see any browning. Done when: The vegetables are soft and see-through at the edges, with no brown color. Onions take 8 to 10 minutes. How to sweat onions (vs. sautéing): mistakes to avoid

   .
   ⏱ Soften onion: 5 min
4. Stir in the garlic until fragrant.
   ⏱ Garlic: 30 sec
5. Whisk (how to whisk)

   Whisk Beat ingredients with a whisk to mix them smoothly or to add air. 1. Use a bowl big enough to whisk without splashing; set it on a damp towel to stop it spinning.2. Hold the whisk loosely and move it in quick circles or side to side, touching the bottom.3. For lumpy mixtures, add liquid a little at a time and whisk after each.4. For sauces on the stove, keep the whisk moving across the whole bottom of the pan. Done when: The mixture is even with no lumps or streaks of egg. How to whisk: mistakes to avoid

   in the flour and cook, whisking, until it smells toasty.
   ⏱ Cook flour: 1 min
6. Slowly whisk in the milk and cream, then add the salt, pepper, nutmeg and thyme.
7. Simmer (how to simmer)

   Simmer Cook liquid just below a boil, with small bubbles breaking the surface now and then. 1. Bring the liquid up over medium-high heat.2. As soon as bubbles rise steadily, turn the heat down.3. Adjust until only a few small bubbles break the surface every second or two.4. Stir now and then and check that it hasn't crept back to a boil. Done when: You see lazy, small bubbles, not a rolling boil. A "bare" simmer has just a bubble here and there. Safety: Steam burns fast: lift lids and foil away from your face, tipping the far edge up first.How to simmer: mistakes to avoid

   , whisking often, until the sauce thickens a little, like heavy cream.
   ⏱ Thicken sauce: 5 min
8. Layer a third of the potato slices in the dish, overlapping them like shingles, and pour a third of the sauce over them. Repeat twice, pressing the top layer down so it's mostly under the sauce.
9. Cover the dish tightly with foil, set it on a sheet pan to catch drips and bake.
   375°F⏱ Bake covered: 45 min
10. Uncover and bake until the top is golden brown and a knife slides through the center with no resistance.
    375°F⏱ Bake uncovered: 35 min
11. Let it

    rest (how to rest)

    Rest Leave cooked meat, baked goods or dough alone for a while before you cut, slice or shape it. 1. Move meat to a board or plate as soon as it is done (a few degrees shy of target for big roasts; it keeps rising).2. Tent it loosely with foil if the kitchen is cool.3. Rest steaks and chops 5 minutes, roasts 15 to 20, a turkey 30.4. For dough, cover it so it doesn't dry out while it relaxes. Done when: Meat juices stay in when you slice; dough rolls out without springing back. Safety: Rest at room temperature for under an hour, then refrigerate leftovers within 2 hours of cooking.How to rest meat and dough: mistakes to avoid

    so the sauce thickens, then sprinkle with parsley and serve.
    ⏱ Rest: 15 min

Tap an underlined word for how to do it, or see all techniques.

Tips

• Want it cheesy? Scatter 1 1/2 cups shredded Gruyère or sharp cheddar between the layers and over the top for a gratin-style dish.
• A mandoline makes quick, even slices; always use its hand guard.
• Russets work too; they turn softer and soak up more sauce.

Storage

Refrigerate within 2 hours, up to 4 days. Reheat portions covered until steaming hot all the way through (165°F). Freezing isn't recommended; the sauce turns grainy.

Make ahead

Bake fully up to 2 days ahead, cool, cover and refrigerate. Reheat covered in a 350°F oven for 35 to 45 minutes, until hot in the center.

How long leftovers keep, and freezing and reheating: leftovers and storage. In season: potatoes (August to November).