Scalloped Potatoes

Ingredients (9)

• 4 pounds Yukon Gold potatoes, thinly sliced into about 1/4-inch thick slices
• 1 medium onion, finely diced or sliced
• 3 tablespoons butter, cut up into smaller cubes, plus more to grease the baking dish
• 3 tablespoons all-purpose flour
• 2 cups milk
• 1/2 teaspoon sea salt
• 1/4 teaspoon pepper
• 1 to 11/2 cups shredded cheddar cheese
• chopped fresh parsley, for garnish