large pastry bag fitted with an open tip #808; large star tip
Arrange a rack in the middle of the oven and preheat to 375 degrees F. Line a baking sheet with parchment paper. Place a stand mixer bowl and whisk attachment in the freezer for your filling.
For the choux dough: Combine the butter, sugar, salt and 1 cup water in a medium saucepan and bring to a boil over medium heat. Remove the pan from the heat and sift the flour directly into the pan. Stir the batter into a paste with a wooden spoon; you will have to beat it hard. Return the pan to medium heat. Stir the batter continuously until it pulls away from the sides of the pan and is slightly shiny, about 3 minutes.
Transfer the batter to a stand mixer bowl fitted with the paddle attachment and beat until slightly cooled, about 3 minutes. Add the eggs, one at a time, incorporating each one thoroughly before adding the next.
Fit a large pastry bag with tip #808 and fill with the choux dough. Pipe twelve 2-inch circular mounds, about 2 inches apart, onto the prepared baking sheet. If the batter has a peak, dab it smooth with a wet fingertip.
Beat the egg yolk with 1 tablespoon of water and brush the surface of the puffs with the beaten yolk.
Bake on the middle rack for 20 minutes, then reduce the oven temperature to 325 degrees F and continue baking until the puffs are golden brown, light, airy and crisp, 30 to 35 minutes more. After you remove the puffs from the oven, flip each over and gently poke the bottom with a paring knife to release the steam. Cool completely on a rack.
For the filling: Remove the stand mixer bowl and whisk attachment from the freezer. Add the cream cheese and sugar to the bowl and beat on high speed until completely combined. Add the heavy cream and vanilla and mix on low speed until mostly combined. Increase the speed to high and whip until soft peaks form. Add the huckleberry jam (or your flavoring of choice) and beat until stiff peaks form.
For the hard candy topper: Line a baking sheet with a silicone mat or foil. Mix the sugar, corn syrup and water together in a heavy-bottomed pot and bring to a boil over high heat. Continue to boil until it reaches the hard crack stage at 300 degrees F. When the candy reaches 300 degrees F stir in a few drops of food coloring. Pour onto the prepared baking sheet. Break the candy into small pieces when it is cool enough to handle.
To assemble: Cut the puffs in half with a serrated knife and set the tops aside. Pipe with a large star tip or spoon the whipped cream filling into the bottom halves of the cream puffs. Replace the puff tops. Top each with a hard candy shard.
You can also add the food coloring to the hard candy once it's poured onto the baking sheet. Use a wood skewer to stir it in for a cool marbled effect. You can also pour it into silicone molds.