Potatoes Au Gratin

Delicately sliced potatoes smothered in a decadent creamy, cheesy sauce with a delectable jolt from nutmeg and thyme, then topped with more cheese. This ultimate potato side dish of all time goes well with just about anything. Utterly delicious and super comforting!

Course Side Dish

Cuisine French

Prep Time 20

Cook Time 45

Total Time 1 5

Servings

Calories 295kcal

Author Imma

Ingredients

2½-3 pounds (1.1-1.3k) potatoes, peeled and thinly sliced (about 7 cups)
3 tablespoons (42g) butter
½ cup (57.5g) onion, chopped
2 tablespoons (16g) garlic, minced
2 teaspoons (2g) fresh thyme
3 tablespoons (30g) all-purpose flour
½ cup (120ml) heavy cream (or sub with milk)
1½ cup (355ml) whole milk
5 ounce (141g) evaporated milk
1 ½ teaspoons (7.5g) salt, or more to taste
black pepper, to taste
¼ teaspoon (0.50g) nutmeg, ground or freshly grated
¾ cup (84.75g) cheddar cheese, shredded
¾ cup (84.75g) Gruyere (or sub with extra cheddar or Jarlsberg)
Sprig of thyme, for optional garnish

Instructions

Preheat oven to 400℉/205℃.
Peel and wash potatoes, then slice into about ⅛" slices. Use a mandolin, if desired, for even and fast prep.
Melt the butter in a large saucepan over medium heat. Add onions, garlic, and thyme. Saute for 1-2 minutes or until fragrant. Be careful not to let the garlic burn.
Whisk in flour until thoroughly combined.
Gently pour in the cream, whole milk, and evaporated milk, followed by salt, pepper, and nutmeg. Bring the cream mixture to a boil and simmer over medium heat, stirring occasionally for about 5 minutes or until the mixture starts to thicken.
Add about ½ cup of shredded cheddar cheese and ½ cup of Gruyere (or Jarlsberg or more cheddar) and stir until smooth. Remove saucepan from the heat.
Grease a 9x13 casserole dish with butter or cooking spray.
Place half of the potatoes in the greased pan, top the potatoes with the sauce, and add the rest of the potatoes and any other remaining sauce.
Cover the dish with foil paper and bake for 45-50 minutes or until potatoes are fork-tender. Take the foil off the dish, sprinkle the remaining cheese over the top, and bake for another 15-20 minutes or until the potatoes are bubbly and brown. Optional: Broil for 5 minutes more for a crustier and browner top.
Top with the thyme sprig, if desired. Serve warm.

Notes

Russet potatoes or Yukon make the best potato choices for this recipe.
To make ahead, simply prepare and assemble the dish up until the baking part, then cover it with foil and put it into the fridge overnight.
Slice the potatoes thinly and uniformly as possible so they'll cook evenly. Using a mandoline will make it easier.
You can microwave the sliced potatoes for about 3-5 minutes to cut the oven time.
Let the au gratin potatoes rest for a few minutes before serving to give them time to settle and firm up a bit.
You can also make this potato au gratin recipe in a crock pot. Assemble as you would in a baking dish and cook on high for 3 hours.
Please remember that nutritional information is a rough estimate and can vary significantly based on the products used.

Nutrition