Nourish PA: Cheesy Scalloped Potatoes

Ingredients

• 1/4 cup (4 tablespoons) unsalted butter, plus more for greasing
• 1 medium yellow onion, chopped
• 2 cloves garlic, minced
• 1/4 cup all-purpose flour
• 1 1/2 cups milk
• 1 cup shredded white cheddar cheese
• 1/2 teaspoon salt
• 3 pounds russet potatoes, or white potatoes, peeled and cut into 1/8-inch-thick slices
• 1 tablespoon chopped fresh parsley (optional)