Prepare the pastry cream. In a medium saucepan mix together milk, sugar, and salt. Bring mixture to a simmer. Stir until the sugar dissolves.
In the meantime, in a separate large bowl whisk cornstarch and egg yolks. Mix a little of the hot milk mixture with egg yolk mixture, whisk constantly as you pour the hot milk to prevent eggs from turning into scrambled eggs. Add a little more milk mixture and continue mixing. Add all the milk and mix. Return milk and egg mixture to the saucepan and bring to a boil. Stir constantly with a wooden spoon until mixture thickens.
Remove from heat and transfer to a heat-resistant bowl. Allow the cream to rest for 10 minutes. Add butter, vanilla, and brandy. Mix until smooth. Strain cream into a bowl. Cover the cream with plastic wrap making sure it touches the surface of the cream so it does not form a skin. Refrigerate.
Pre heat oven to 425°F. Line 3 baking sheets with parchment paper.
In a medium sized saucepan place the water, butter, sugar, and salt and bring to a boil. Once the butter is melted, add the flour and mix with a wooden spoon until a dough is formed. Keep the mixture on a medium heat and mix vigorously until the dough starts to pull away from the sides and has firmed up a little.
In the bowl of an electric mixer fitted with the paddle attachment, place the dough and beat on low speed until the dough cools down. About 5 minutes.
With the mixer at medium speed, add the eggs, one at a time, allowing each egg to fully incorporate into the dough. If a mixer is not available, the same can be accomplished in a mixing bowl and a wooden spoon. Once the dough is mixed, place in a pastry bag and cut a ½-inch hole at the end of the bag.
Squeeze out the dough onto the prepared baking sheets. Pipe out dough until you have a 1 ½-inch round. Repeat the process making sure the puffs are at least 1 ½ inches apart. You will have around 35-40 puffs. Dip your finger in water and push down any peaks may have formed on the puffs from piping.
Place puffs into oven at 425°F for 10 minutes, or until they have puffed up and have a firm exterior. At this point, turn the oven down to 300°F and cook for an additional 10 minutes or until golden brown.
Remove from oven and cool on a rack.
Poke a small hole into the bottom of each puff with a paring knife. Transfer cold pastry cream into a pastry bag fitted with a plain pipping tip with ½-inch opening; fill the cream puffs with pastry cream and set aside.
Prepare chocolate ganache. Heat a small pot with several inches of water and place a glass bowl with white chocolate chips and butter inside to create a double boiler. Allow the chocolate to melt in the bowl, stirring occasionally, until it is completely melted. Remove from heat and continue to stir until it reaches a smooth consistency.
Prepare the plate in which you will serve the croquembouche with a 7-inch round piece of parchment paper to use as a guide.
Dip the top of the filled puffs in the chocolate ganache and place, chocolate side up, in a cooling rack. Dip some puffs in sanding sugar, some in nonpareils and leave some plain with chocolate. Let puffs stand for 30 minutes to allow chocolate to set. To assemble the croquembouche, dip the side of one puff melted chocolate; you are using the chocolate as glue. Place enough puffs around the parchment paper circle making sure you cover the circle. This is the base of the tower. The top of the puff should face out. When you finish with the base, repeat the process of building the croquembouche making smaller circles for each layer. Finish tower with one puff. If the chocolate becomes too thick, heat it up at low heat in the microwave to loosen it up. Decorate with edible pearls and fondant stars.