Grandma’s Roasted Garlic Potatoes Gratin

A cozy, old-fashioned potato gratin layered with tender potatoes, roasted garlic, cream, Parmesan, and melted cheese. The top turns beautifully golden and crisp while the inside stays rich, creamy, and tender.

Ingredients

For the roasted garlic:

• 1 whole garlic bulb
• 1 tsp olive oil
• Pinch of salt

For the potato gratin:

• 2½ lb (1.1 kg) Yukon Gold potatoes
• 1½ cups heavy cream
• ½ cup whole milk
• 1 cup shredded Gruyère cheese
• ½ cup freshly grated Parmesan cheese
• 2 tbsp unsalted butter
• 1 tsp fresh thyme leaves
• ½ tsp dried rosemary
• 1 tsp salt
• ½ tsp black pepper
• ¼ tsp nutmeg, optional
• 1 tbsp chopped fresh parsley

Instructions

1. Roast the garlic
   Preheat the oven to 400°F (200°C). Slice the top off the garlic bulb to expose the cloves. Drizzle with olive oil and sprinkle with a pinch of salt.

Wrap the garlic loosely in foil and roast for 35–45 minutes, until the cloves are soft, golden, and fragrant. Let cool slightly, then squeeze the roasted garlic from the skins and mash into a smooth paste.

2. Prepare the potatoes
   Peel the potatoes if desired and slice them very thinly, about ⅛ inch (3 mm) thick. A mandoline makes this easier and gives the potatoes an even cooking time.

Do not rinse the sliced potatoes because the natural starch helps thicken the creamy sauce.

3. Make the garlic cream
   In a saucepan over medium-low heat, combine the heavy cream, milk, roasted garlic, thyme, rosemary, salt, pepper, and nutmeg.

Warm gently for 3–4 minutes. Do not bring it to a vigorous boil.

4. Prepare the baking dish
   Preheat the oven to 375°F (190°C). Grease a 9×13-inch baking dish with butter.
5. Layer the potatoes
   Arrange a layer of sliced potatoes across the bottom of the dish. Sprinkle with a little Gruyère and Parmesan.

Continue layering the potatoes and cheese until everything is used.

6. Add the cream
   Slowly pour the roasted garlic cream mixture over the potatoes, making sure it reaches throughout the layers.

Press the potatoes gently down so they are mostly coated with the cream.

7. Add the final cheese
   Dot the top with the remaining butter and sprinkle generously with the remaining Gruyère and Parmesan.
8. Bake covered
   Cover the dish tightly with foil and bake for 45 minutes.
9. Bake uncovered
   Remove the foil and continue baking for another 25–35 minutes, until the potatoes are completely tender and the top is deeply golden and bubbling.
10. Rest
    Let the gratin rest for 10–15 minutes before serving. This allows the creamy sauce to thicken and makes it easier to cut into portions.
11. Garnish
    Sprinkle with fresh parsley and a little extra Parmesan before serving.

Tips

• Slice the potatoes evenly so they cook at the same rate.
• Yukon Gold potatoes give the gratin a naturally buttery texture.
• Don’t skip the resting time.
• Freshly grated cheese melts more smoothly.
• Keep the cream mixture warm but avoid boiling it.
• For an extra-crispy top, broil for 1–2 minutes at the end, watching carefully.

Optional Additions

• Cooked crispy bacon
• Caramelized onions
• Sautéed mushrooms
• Fresh spinach
• Chopped ham
• Extra Gruyère
• A pinch of chili flakes

Nut Information

• Contains nuts: No.
• This recipe contains dairy.
• Parmesan and Gruyère are dairy products, not nuts.
• If preparing for someone with a nut allergy, check packaged cheese, cream, butter, and seasonings for possible cross-contact warnings.

Q&A

Q: Can I use Russet potatoes?
A: Yes. Russets work well and create a softer, starchier gratin. Yukon Gold potatoes give a creamier and more buttery texture.

Q: Can I prepare this ahead of time?
A: Yes. Assemble the gratin, cover tightly, and refrigerate for up to 24 hours. Allow it to sit at room temperature for about 20–30 minutes before baking.

Q: Can I use regular garlic instead of roasted garlic?
A: Yes, but roasted garlic gives the dish a sweeter, deeper flavor. If using fresh garlic, finely mince 3–4 cloves and add them to the cream.

Q: Why are my potatoes still hard?
A: The slices may be too thick, the dish may not have been covered long enough, or your oven temperature may run low. Continue baking covered until fork-tender.

Q: Can I use cheddar instead of Gruyère?
A: Absolutely. Sharp cheddar, white cheddar, Monterey Jack, or Fontina can be used.

Q: Can I make this without heavy cream?
A: Yes. Use half-and-half for a lighter version, although the gratin may be slightly less rich.

Q: Can I freeze potato gratin?
A: It can be frozen, but the creamy sauce may change texture slightly after thawing. For the best texture, refrigerate leftovers instead.

Q: How do I store leftovers?
A: Refrigerate in an airtight container for up to 3–4 days.

Q: How do I reheat it?
A: Cover with foil and reheat in a 350°F (175°C) oven until hot. Add a splash of cream or milk if it seems dry.