Mix Dry: Whisk together cake flour, sugar, baking powder, salt, and nutmeg in a large bowl.
Mix Wet: In another bowl, mix sour cream, eggs, melted butter, and milk until smooth.
Combine: Gently fold wet ingredients into dry ingredients until just combined. Don’t overmix to keep them tender.
Chill: Wrap dough and chill for 1 hour (نصيحة إضافية للأرشفة).
Cut: Roll dough to ½-inch thickness and cut with a doughnut cutter.
Fry: Heat oil to 350-375°F. Fry for 1-2 minutes per side until golden brown.
Glaze: Whisk glaze ingredients. Dip warm doughnuts and let set on a wire rack.