- 2 lbs (900g) russet or Yukon Gold potatoes, thinly sliced (about ⅛-inch thick)
- 2 tablespoons unsalted butter
- 1 small onion, finely chopped
- 2 cloves garlic, minced
- 1 ½ cups (360ml) heavy cream (or half-and-half for a lighter version)
- 1 cup (240ml) whole milk
- ½ teaspoon salt
- ½ teaspoon black pepper
- ½ teaspoon dried thyme (or 1 teaspoon fresh)
- ¼ teaspoon nutmeg (optional, adds warmth)
- 1 ½ cups shredded cheddar cheese (or Gruyère for a richer flavor)
- ½ cup grated Parmesan cheese
- 1 tablespoon chopped fresh parsley (for garnish)