In a heavy saucepan, combine brown sugar, butter, and whipping cream. Cook over low heat until the brown sugar just dissolves, stirring occasionally. Pour mixture into two 9x1-1/2-inch round baking pans. Sprinkle evenly with the pecans. Let the mixture cool slightly.

In a bowl, stir together the flour, baking powder, pumpkin pie spice, baking soda, and salt. Set it aside.

In a large mixing bowl, beat together the granulated sugar, cooking oil, and eggs. Add the pumpkin and dry ingredients alternately to the oil mixture, beating until the mixture is just combined. Stir in the black walnut flavoring, if you like.

Carefully spoon the batter over the pecan/ brown-sugar mixture in the baking pans. Place pans on a baking sheet. Bake in a 350 degree F oven for 35 to 40 minutes or until toothpicks inserted in the centers come out clean. Cool the cakes in pans on wire racks for 5 minutes. Invert them onto wire racks, replacing any brown-sugar mixture that remains in the pans. Cool before assembling.

Meanwhile, prepare the Whipped Cream Topping.

To assemble the cake, place one cake layer on a serving plate, praline side up. Spread with the topping. Add the second layer, praline side up. Pipe or dollop with the remaining topping. Sprinkle lightly with some additional pie spice, if you like. Makes 12 servings.

In a clean mixing bowl, beat 1-3/4 cups whipping cream with an electric mixer until soft peaks form (tips curl). Add 1/4 cup sifted powdered sugar and 1/4 teaspoon vanilla. Beat the topping mixture until stiff peaks form (the tips stand straight).

8. Note: Plan to assemble this cake no more than 1-1/2 hours before serving, so the whipped cream doesn't break down. Keep the cake chilled until it's served.