In a medium saucepan, whisk together the milk, half the sugar (1/4 cup), cornstarch, and salt until smooth. Heat this mixture over medium heat until it starts to simmer. In a separate bowl, whisk together the egg yolks and the remaining sugar. Gradually add a few spoonfuls of the hot milk mixture into the yolks to temper them, then pour the yolk mixture back into the saucepan.
Continue to cook the mixture over medium heat, whisking constantly until it thickens and starts to bubble. Remove from heat and stir in the vanilla extract. Cover with plastic wrap directly on the surface and let it cool in the refrigerator.
In another saucepan, combine the water, diced butter, sugar, and salt. Bring to a boil over medium heat. Once boiling, remove from heat and add the flour all at once. Stir vigorously until the mixture forms a ball and pulls away from the sides of the pan.
Let the dough cool slightly before adding the eggs one at a time, mixing well after each addition until fully incorporated. Add 2 to 3 drops of red food coloring to give the dough that signature pink hue.
Preheat your oven to 400°F (200°C). Transfer the choux pastry to a piping bag fitted with a large round tip. Pipe small mounds (about 1.5 inches wide) onto a baking sheet lined with parchment paper, leaving space between each puff.
In a small bowl, whisk together the extra large egg with 1 tablespoon of water. Brush the tops of the puffs with the egg wash for a beautiful golden color.
Bake in the preheated oven for about 20-25 minutes, or until the puffs are golden brown and puffed up. Do not open the oven door while they bake, as this can cause them to deflate.
Once baked, remove the puffs from the oven and let them cool completely on a wire rack. Once cool, use a small knife to cut a slit in the side of each puff and fill them with the chilled pastry cream using your piping bag.
Dust the filled Jigglypuff Pink Cream Puffs with powdered sugar for a finishing touch and serve immediately. Enjoy the delightful blend of flavors and textures as you take a bite!