Heat oven to 325°F. In 1-quart heavy saucepan, stir together butter, whipping cream and brown sugar. Cook over low heat, stirring occasionally, just until butter is melted. Pour into 2 (9- or 8-inch) round cake pans; sprinkle evenly with 3/4 cup pecans.

In large bowl, beat cake mix, pumpkin, water, oil, eggs and 1 teaspoon of the pumpkin pie spice with electric mixer on low speed until moistened. Beat 2 minutes on medium speed. Carefully spoon batter over pecan mixture in each pan.

Bake 43 to 45 minutes or until cake springs back when touched lightly in center. Cool 5 minutes; remove from pans to cooling rack. Cool completely, about 1 hour.