For caramel: Combine butter, cream, and brown sugar in a small saucepan. Cook over low heat just till butter is melted, stirring occasionally.

Pour evenly into two 9" round cake pans that have been sprayed with non-stick cooking spray. Sprinkle the chopped pecans evenly between the two pans.

For cake: Combine cake mix, water, oil, and eggs in a large mixing bowl. Beat two minutes, then divide batter evenly between the two pans.

Bake at 325° for about 40-45 minutes or until toothpick comes out clean. Let cool 5 minutes in pan, then invert onto cooling racks. Cool completely.

For topping: Beat whipping cream till peaks form, then beat in powdered sugar and vanilla. Beat till stiff peaks form.

To assemble cake: Place first layer on a serving plate, nut side up. Top with half of the caramel sauce, letting some drip down the side. Spread half of the whipping cream over the caramel. Top with the second cake layer.

Repeat caramel and cream layers. Top with chocolate curls or shavings if desired.