A twist on the traditional pastry case favorite inspired by a classic king cake.
For the Choux Pastry: Preheat the oven to 400°F. Combine the butter, water, sugar, cinnamon, and salt into a medium-sized saucepan and bring to a boil. You want the butter to be fully melted at the same time that the water begins to boil—if it's not there yet, stir until it melts. Add the flour all at once, and, moving quickly, stir with a wooden spoon until a dough forms. Continue stirring for about a minute, until the dough becomes glossy.
Trasfer mixture to the bowl of a stand-mixer and beat at a low speed for a minute or two, to allow the dough to cool slightly. Add eggs, one at a time, allowing them to fully incorporate into the dough. After three eggs, check the dough by running your finger through it at the bottom of the bowl. You're looking for a dough that springs back to close the channel you made. Add remaining eggs until it does so.
Cover a baking sheet with parchment paper. Transfer the dough to a piping bag with a large round tip. You're looking for an opening of 1/3- to 1/2-inch. Pipe roughly 3-inch long fingers of dough onto the baking sheet about an inch apaprt. Bake at 400°F for 20 minutes and reduce oven temperature to 350°F. Bake for another 15 minutes, or until the eclairs are crisp. if they're still moist in the middle, use a skewer or paring knife to make small holes in the bottom of the exlairs to allow the steam to escape. Let cool on a wire rack.
For the Pastry Cream: Combine milk and vanilla in a medium saucepan and bring to a simmer. Meanwhile, whisk the egg yolks together with the sugar. Once they have been thoroughly incorporated, add the cornstartch and whisk until a smooth mixture forms.
Once the milk and vanilla simmers, add roughly a third of the hot milk mixture to the cornstarch, egg yolks, and sugar mixture, whisking continuously. Pour the cornstarch mixture into the pot with the rest of the milk, and continue to whisk over low heat until the mixture thickens. Stir in the cream cheese until it melts and forms a smooth cream. Pour into a mixing bowl and cover with plastic to prevent a skin from forming, chill until needed.
For the Glaze: Add the milk and corn syrup (if desired, just for a glossier glaze) together in a bowl. Whisk in the milk, one tablespoon at a time, until a thick glaze forms. Separate the glaze into three bowls and add food coloring to make purple, green, and yellow glazes.
To Assemble the Eclairs: Transfer the pastry cream to a piping bag with a small round tip, ideally around 1/4 inch. using a paring knife, make three small holes along the length of the bottom of the exlair. Pipe the pastry cream into the eclairs until they feel heavy. Use a spoon to drizzle the glaze onto the eclairs. Let set, and enjoy.