Preheat oven to 350 degrees. Spray a 9-inch square pan with cooking spray.

With an electric mixer, cream sugar and butter together until light and fluffy. Add egg and vanilla, mix well. Mix in flour, baking soda, cinnamon, nutmeg and salt until just combined. Stir in grated apples and mix well.

Spread batter into prepared pan and bake for 30-35 minutes or until a toothpick comes out clean.

Meanwhile, make the caramel sauce: in a medium saucepan, melt butter over medium heat. Add brown sugar and whisk for 1 minute. Add the salt and cream and bring mixture to a boil, stirring constantly. Boil for 4 minutes. Remove from heat and stir in vanilla. Allow to cool slightly.

Serve cake warm with warm caramel sauce drizzled over the top.