Heat oven to 400°F. Grease cookie sheet.

Combine water, butter and salt in medium saucepan; cook to boiling, stirring until butter melts. Add flour all at once; stir vigorously over low heat about 1 minute or until mixture leaves the side of pan and forms a ball. Remove from heat.

Add eggs, one at a time, beating with spoon after each addition until smooth. Drop dough by heaping tablespoons into 6 mounds, 3 inches apart, onto prepared cookie sheet.

Bake 25 to 30 minutes or until golden brown. Remove from cookie sheet to wire rack. Horizontally slice small portion from top of puffs; set tops aside. Remove and discard any soft dough from inside puffs. Cool completely. Fill puffs with the chocolate mousse; replace tops. Refrigerate about 1 hour and sprinkle the top with powdered sugar just before serving. Makes about 6 puffs.