Preheat oven to 450°. Bring water, margarine and salt to boil in small saucepan. Add flour all at once. Stir vigorously, cooking until mixture leaves sides of pan and forms a ball. Remove from heat. Cool 2 minutes. Add eggs, one at a time, beating until mixture is thick and shiny. Using rounded teaspoon, drop dough 2 inches apart onto lightly greased baking sheet. Bake in preheated oven 15 minutes. Lower heat to 350° and bake 20 minutes. Split 1 puff to check for doneness; if too doughy on inside, return to oven and bake a few more minutes. Transfer to rack and cool completely. Store in airtight container at room temperature until time to use.
To assemble: Just before serving, heat chocolate sauce. Meanwhile split puffs and fill with whipped cream. Place filled puffs on individual serving plates. Pour chocolate sauce over filled puffs. Pass extra chocolate sauce.