Classic Potatoes Dauphinoise — Creamy Garlic-Gratin Roast Beef Side

How to Make Classic Potatoes Dauphinoise — Creamy Garlic-Gratin Roast Beef Side

1. 1

   Step 1: Slice potatoes and infuse the cream

   Preheat the oven to 350°F (175°C). Peel the potatoes and, using a mandoline set to 1/8" (3 mm) or a very sharp knife, slice them uniformly—consistent thickness ensures even cooking (tip: trim a small flat on the potato so it sits steady on the mandoline). Place slices in a large bowl of cold water to remove excess starch. Meanwhile, combine the heavy cream, milk, smashed garlic, and thyme in a saucepan with 1 tsp of the kosher salt; warm gently until just under a simmer, then remove from heat and keep hot while you assemble.

   For this step

   • 2 1/2 lbYukon Gold potatoes, peeled
   • 3 clovesGarlic cloves, smashed
   • 2 tspFresh thyme leaves (plus sprigs for garnish)
   • 1/2 cupWhole milk
2. 2

   Step 2: Par-blanch the slices and prep the dish

   Drain the potato slices and bring a large pot of cold water with the remaining 1 tsp salt to a gentle simmer. Add the slices and simmer 2–3 minutes to take the raw edge off, then immediately drain and pat dry with a kitchen towel. Butter a 9x13-inch (or similar volume) baking dish with about 1 tbsp of the butter. Layer a single, slightly overlapping layer of potato slices in the dish, season lightly with pepper and a pinch of salt, and spoon some of the hot cream over — repeat, finishing with a thin layer of slices.

   For this step

   • 1/2 tspFreshly ground black pepper
3. 3

   Step 3: Add cheese, cream and bake

   Between layers or sprinkled on top, distribute about two-thirds of the grated Gruyère; reserve the rest for the finish. Pour the remaining hot cream so it comes about three-quarters up the sides of the top layer (the potatoes will swell as they cook). Dot the top with the remaining 1 tbsp butter, cover tightly with foil, and bake for 45–55 minutes at 350°F (175°C), or until a knife slides easily into the center and the potatoes are tender.

   For this step

   • 1 1/2 cupsGruyère cheese, grated
   
4. 4

   Step 4: Brown and rest

   Remove the foil, sprinkle the reserved Gruyère evenly over the top, and increase the oven to 425°F (220°C) or switch to broil. Brown the top 6–8 minutes until bubbling and golden—watch closely to avoid burning. Let the gratin rest 10–15 minutes out of the oven (this helps it set so it slices cleanly). Garnish with fresh thyme leaves and serve warm alongside roast beef.
   
5. 5

   Step 5: Make-ahead and reheating tips

   This gratin is make-ahead friendly: assemble in the baking dish, cover tightly and refrigerate up to 24 hours. If baking from cold, add 15–20 minutes to the covered bake time and then uncover to brown. To reheat cooked gratin, cover and warm in a 350°F (175°C) oven for 20–30 minutes or until heated through; finish under the broiler 2–4 minutes to refresh the crust.
   
6. 6

   Step 6: Tips for texture and variations

   For uniform slices use a mandoline or guide the knife with a ruler on a steady potato; thinner slices give creamier texture, thicker slices a more rustic bite. For a richer gratin: use all heavy cream (substitute the milk) and increase Gruyère by 1/4 cup, or stir an egg yolk into a cup of warm cream before pouring for extra silkiness. For a lighter version: use half-and-half or a higher ratio of milk to cream, reduce the cheese by 1/4 cup, and increase herbs (shallot, extra thyme) for flavor without extra fat.
   

1. Preheat the oven to 350°F (175°C). Peel the potatoes and, using a mandoline set to 1/8" (3 mm) or a very sharp knife, slice them uniformly—consistent thickness ensures even cooking (tip: trim a small flat on the potato so it sits steady on the mandoline). Place slices in a large bowl of cold water to remove excess starch. Meanwhile, combine the heavy cream, milk, smashed garlic, and thyme in a saucepan with 1 tsp of the kosher salt; warm gently until just under a simmer, then remove from heat and keep hot while you assemble.
2. Drain the potato slices and bring a large pot of cold water with the remaining 1 tsp salt to a gentle simmer. Add the slices and simmer 2–3 minutes to take the raw edge off, then immediately drain and pat dry with a kitchen towel. Butter a 9x13-inch (or similar volume) baking dish with about 1 tbsp of the butter. Layer a single, slightly overlapping layer of potato slices in the dish, season lightly with pepper and a pinch of salt, and spoon some of the hot cream over — repeat, finishing with a thin layer of slices.
3. Between layers or sprinkled on top, distribute about two-thirds of the grated Gruyère; reserve the rest for the finish. Pour the remaining hot cream so it comes about three-quarters up the sides of the top layer (the potatoes will swell as they cook). Dot the top with the remaining 1 tbsp butter, cover tightly with foil, and bake for 45–55 minutes at 350°F (175°C), or until a knife slides easily into the center and the potatoes are tender.
4. Remove the foil, sprinkle the reserved Gruyère evenly over the top, and increase the oven to 425°F (220°C) or switch to broil. Brown the top 6–8 minutes until bubbling and golden—watch closely to avoid burning. Let the gratin rest 10–15 minutes out of the oven (this helps it set so it slices cleanly). Garnish with fresh thyme leaves and serve warm alongside roast beef.
5. This gratin is make-ahead friendly: assemble in the baking dish, cover tightly and refrigerate up to 24 hours. If baking from cold, add 15–20 minutes to the covered bake time and then uncover to brown. To reheat cooked gratin, cover and warm in a 350°F (175°C) oven for 20–30 minutes or until heated through; finish under the broiler 2–4 minutes to refresh the crust.
6. For uniform slices use a mandoline or guide the knife with a ruler on a steady potato; thinner slices give creamier texture, thicker slices a more rustic bite. For a richer gratin: use all heavy cream (substitute the milk) and increase Gruyère by 1/4 cup, or stir an egg yolk into a cup of warm cream before pouring for extra silkiness. For a lighter version: use half-and-half or a higher ratio of milk to cream, reduce the cheese by 1/4 cup, and increase herbs (shallot, extra thyme) for flavor without extra fat.