Preheat Oven to 375º. For puffs, in a (1.5 – qt) saucepan, combine water, butter and salt; bring to a boil over high heat. Add flour all at once. Stir mixture vigorously about 1 minute or until mixture leaves sides of pan and forms into a ball. Remove from heat; whisk eggs in a separate bowl. Add dough into eggs and whisk until smooth and very thick.
Lightly spray mini muffin pan w/cooking spray. Using a small cookie scoop form slightly mounded scoops into prepared pans. Bake 22-25 minutes or until deep golden brown (do not open oven door while baking or they won’t rise properly). Make a small cut on the side of each puff to release excess steam. Remove puffs from pan to a wire rack.
For filling, combine whipped topping, powdered sugar and vanilla. Mix gently until well blended. Put filling into a pastry bag, fitted with a small round tip. Locate the small cut made in each puff and pipe in filling.
For topping place chocolate chips with butter in a microwave safe bowl, place in microwave for 30 seconds, stir if needed returned to microwave to continue melting chips (if you scorch chocolate chips add an additional tbl of butter and stir until smooth) Drizzle over filled puffs. Optional 2 tbl chopped pistachios or shake powdered sugar on top after chocolate has been drizzled on.
Freeze until ready to serve these can be made well in advance of serving. Thaw for 15 minutes before serving.