1. Preheat oven to 375° F. In a saucepan, combine 1 cup of water, butter, sugar and salt over medium heat. 
2. Bring to a boil, and quickly add the flour. Begin stirring vigorously with a wooden spoon over low heat until the dough begins to pull away from the sides of the pan and comes together in a ball. Continue stirring for 2 minutes until a film forms on the bottom of the pan.
3. Remove from heat, and transfer dough to a bowl. 
4. Let cool for 5 minutes. Begin adding 4 of the eggs, one at a time. Let each egg thoroughly incorporate before adding another. The dough should be smooth, glossy and thick enough to hold a peak. 
5. Transfer dough to a piping bag fitted with a 5/8-inch tip. Pipe dough into 1 1/2-inch circles (28 total) onto parchment-lined baking sheets. 
6. Make the egg wash by combining the remaining egg with 1 tablespoon of water. Brush the tops, and smooth down any pointed peaks created from piping. 
7. Bake for 30 to 35 minutes until puffs rise and are golden-brown. Let cool before filling. 
8. Whip the cream to stiff peaks. Fold in the lemon curd and zest. Fill the puffs with cream. (Puffs can be filled two ways. One way is by cutting the puff in half and spooning cream into the center. The other way is to fill a piping bag with the cream. Cut a small “x” on the bottom of each puff, and pipe the cream into the center.)
9. Sprinkle the puffs with powdered sugar before serving.

Per Serving (2): 

Calories: 260, Fat: 22 g (13 g Saturated Fat), Cholesterol: 125 mg, Sodium: 125 mg, Carbohydrates: 8 g, Fiber: 0 g, Protein: 4 g