Preheat oven to 375 degrees. Line two baking sheets with parchment paper or baking mats. Set aside.
In a medium saucepan, heat butter, sugar, salt, and water together over medium-high heat until it boils. Immediately add all of the flour and stir with a wooden spoon. Continue to stir over heat until a firm forms on the bottom of the pan. Remove from heat and transfer dough to a medium bowl to cool down for 3 minutes.
Once slightly cooled, add 1 egg to dough and stir vigorously until combined into dough. Repeat with rest of eggs, one at a time.
Transfer mixture to a large pastry bag fitted with a large piping tip. Pipe 1 1/2 inch rounds onto prepared baking sheets (about the size of a macaron). Make sure to space out about 2 inches apart. Dip your finger into water and smooth out the tops of each dollop of dough.
Gently brush each dollop with egg wash. Bake puffs for 30 minutes until they've risen and turn golden brown on top. Once finished, remove from oven and let cool completely before filling.
Once the puffs are cooled and the pastry creme is chilled, it's time to assemble! Place pastry cream in a pastry bag fitted with a small round tip. Using a pairing knife, cut an X into the bottom of the puff. Stuff the x with the tip of the pastry cream bag and squeeze the pastry cream into the puff until you feel that it's full. Repeat with the rest of the puffs.
Once all puffs are filled, melt the 6 ounces of white chocolate chips in a small bowl by microwaving for 30 seconds. Stir and microwave another 30 seconds. Dip the tops of each puff into melted white chocolate and place on wire racks to let the chocolate harden. Serve immediately or within 24 hours.