1 pkg. chocolate cake mix
2/3 c. water
3 tbsp. vegetable oil
2 eggs
1 3/4 c. chilled whipping cream
2/3 c. miniature marshmallows
2/3 c. coarsely chopped walnuts (optional)
1/2 c. semi-sweet chocolate chips

Heat oven to 350 degrees. Grease and dust with sugar a pie plate, 9 x 1 1/4 inches. Reserve 1 2/3 cups lightly packed dry cake mix. Beat remaining cake mix, water, oil, and eggs in medium bowl on low speed, scraping bowl constantly, 30 seconds. Beat on medium speed, scraping bowl frequently, 2 minutes. Spread in pie plate. Bake until cake springs back when touched lightly in center, 30 to 35 minutes; cool completely. Beat whipping cream and reserved dry cake mix until stiff. Fold in marshmallows, walnuts, and chocolate chips. Spread over cooled cake. Refrigerate at least 2 hours before serving. Refrigerate any remaining dessert.