In a 2- to 3-quart pan, combine 3/4 cup water, 6 tablespoons butter, and sugar. Bring to a boil over high heat.
When butter is melted, remove from heat and add flour all at once. Beat with a sturdy spoon until well blended. Return pan to heat and stir vigorously until mixture forms a ball and leaves sides of pan, 1 to 2 minutes. Let mixture cool for 5 minutes.
Transfer the mixture to a food processor, or leave in pan. Add eggs 1 at a time; whirl or beat until smooth after each addition. Let the batter cool 10 minutes.
With a spoon, drop batter in 8 (1/4 cup) to 10 (slightly more than 3 tablespoons) portions at least 2 inches apart on a lightly buttered 14- by 17-inch baking sheet.
Bake in the center of a 375° oven until brown and firm when pressed, about 45 minutes (about 30 minutes in a convection oven). Remove pan from oven and quickly cut the top 1/3 off each puff, then set back in place. Return to oven and bake until puffs are crisper and slightly browner, about 10 more minutes. Cool on racks.
Scoop out and discard moist interiors of puffs and fill the hollows with ice cream. Set cream puff tops on the ice cream and set puffs on plates. Drizzle with chocolate sauce, add dollops of whipped cream, and sprinkle with nuts.