Cream puffs never go out of style, but we added espresso powder to give these a new flavor. To lighten them, we decreased the butter in the puffs and used fat-free milk. We also added gelatin and whipped topping to the pastry cream for an incredibly light and creamy filling that holds up well.
To prepare cream puffs, lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, 2 teaspoons sugar, and 1/4 teaspoon salt; set aside. Combine 1 cup milk, butter, and espresso granules in a large saucepan; bring to a boil. Reduce heat to low; add flour mixture, stirring well until mixture is smooth and pulls away from sides of pan. Remove mixture from heat. Add eggs and egg white, 1 at a time, beating well with a wooden spoon until smooth.
Drop the dough by level tablespoons, 2 inches apart, onto baking sheets coated with cooking spray. Bake at 400° for 10 minutes. Reduce oven temperature to 350°; bake an additional 10 minutes or until browned and crisp. Remove from oven; pierce the side of each cream puff with the tip of a sharp knife. Turn oven off; let cream puffs stand in partially closed oven for 20 minutes. Remove from baking sheet; cool completely on a wire rack.
To prepare pastry cream, sprinkle gelatin over water in a small bowl; set aside. Combine 3/4 cup milk and next 5 ingredients (milk through egg yolks) in a medium saucepan. Place over low heat; cook until warm, stirring constantly. Stir in gelatin mixture; cook over medium heat until thick (about 8 minutes), stirring constantly. Remove from heat. Place pan in a large ice-filled bowl; let stand 15 minutes or until room temperature (do not allow mixture to set). Remove pan from ice. Gently whisk in whipped topping. Cover and chill 4 hours or until thick.
Cut tops off cream puffs; fill each cream puff with 1 tablespoon filling. Sprinkle with powdered sugar, if desired.