Preheat the oven to 350 degrees. In a bowl and with an electric mixer, cream together the brown sugar and butter until smooth and fluffy. Add the eggs, vanilla, baking soda, salt, cinnamon, nutmeg to the butter/sugar and whip until smooth. Dice the apples into small pieces. Add the applesauce and diced apples to the batter. Add the flour slowly until the batter is combined.
Spray a 9x13 pan with nonstick cooking spray. Bake at 350 for 35-40 minutes, or until a toothpick comes out clean from the center.
For the sauce, add the butter, sugar and whipping cream into a saucepan and heat to medium high heat. Simmer the sauce until the sugar dissolves and the sauce is creamy. Drizzle this glaze over the warm cake from the oven.