HEAT oven to 325 degrees F. Combine butter, 1/4 cup cream and brown sugar in small heavy saucepan. Cook over low heat just until butter is melted, stirring occasionally. Pour into two 8 or 9-inch round cake pans; sprinkle evenly with chopped pecans. PREPARE cake as directed, using water, oil, and eggs. Carefully spoon batter over pecan mixture. BAKE 35 to 45 minutes or until cake springs back when touched lightly in center. Cool 5 minutes; remove from pans. Cool 1 hour or until completely cooled. BEAT 1 3/4 cups cream in small bowl until soft peaks form. Add powdered sugar and vanilla; beat until stiff peaks form. PLACE 1 layer on serving plate, praline side up. Spread with half of whipped cream. Top with second layer, praline side up; spread top with remaining whipped cream. Garnish with whole pecans and chocolate curls. Store in refrigerator. High Altitude (above 3500 ft.): SEE cake package for directions. Immediately remove from pans.