Preheat oven to 350°F (175°C). Grease and line an 8-inch cake pan with parchment paper.
Mix wet ingredients: In a bowl, stir together applesauce and condensed milk until smooth.
Add flour: Fold in the self-rising flour gently. The batter will be thick but spreadable. Don’t overmix or the cake may turn dense.
Optional extras: Stir in sliced apples, walnuts, or raisins if you like.
Bake: Spread the batter evenly in the pan. Bake for 30–35 minutes or until a toothpick inserted in the center comes out clean.
Cool: Let the cake cool in the pan for 10 minutes, then transfer to a wire rack.
Serve: Slice and enjoy as is, or dust with powdered sugar.