Preheat oven to 325 degrees F. Spray a round 8-inch springform pan. Line the bottom of the pan with parchment paper. Set the round pan on on a baking sheet, also lined with parchment paper, and set aside.

In a large electric mixing bowl, cream the room temperature butter along with the brown sugar. When the mixture is smooth, add the eggs, one at a taime. Blend the eggs until well mixed, but do not over beat.

In another large bowl, whisk together the ground hazelnuts, flour, baking powder, salt, nutmeg. Once the dry ingredients are blended, slowly add the dry mixture to the butter/egg batter. Combine well without overbeating. With a spoon, fold in the shredded apples.

Pour batter in the prepared pan. Top with the brown sugar and ground hazelnuts, making sure it's evenly distributed. Keeping the pan on the baking sheet, place the baking sheet into the oven. Bake for 65-80 minutes. Watch for the cake to turn a gold color and for the sides to begin to pull away from the edges of the pan. It's done when a toothpick pushed into the center of the cake comes out clean. (time differential is determined by the amount of moisture in the apples)

Remove from oven and set the baking sheet, with the pan, on a baking rack to rest for 5 minutes.

After five minutes, run a sharp knife around the inside edge of the pan and remove the outer ring. Let cool for another 10-20 minutes for the cake to set.

For the toffee sauce, set up a double boiler. Over medium heat, melt the brown sugar and butter and whipping cream. Stir with a wooden spoon until melted and well blended. Stir in vanilla and remove from heat. Serve immediately over the cake. The cake can be either warm or room temperature. But make sure you let the cake rest before you cut it or else it will crumble. The sauce will also keep in the fridge and can be reheated in the microwave when needed.