Turkey, Potato, and Onion Casserole

Ingredients (13)

• + 2 ½ pounds russet potatoes, peeled and cut into 1/4-inch slices add to pantry
• + 1 pinch salt to taste add to pantry
• + 2 cups diced cooked turkey add to pantry
• + 1 tablespoon extra-virgin olive oil add to pantry
• ✓ 1 medium onion, sliced horizontally
• + ¼ cup unsalted butter add to pantry
• + 3 tablespoons all-purpose flour add to pantry
• + 1 ⅔ cups turkey stock add to pantry
• + 1 ½ cups grated Parmigiano-Reggiano cheese add to pantry
• + 1 cup sour cream add to pantry
• + ¼ teaspoon ground black pepper, or to taste add to pantry
• + ½ cup bread crumbs add to pantry
• + 2 tablespoons chopped fresh parsley, or to taste add to pantry