In a medium saucepan over medium-high heat, combine the water, butter, 2 tablespoons sugar, and the salt, and bring to a boil.
As soon as the mixture begins to boil, reduce the heat to medium-low and add the flour. Using a wooden spoon, stir until the dough comes together to form a ball, about 1 minute.
Remove the pan from the heat and let cool for 5 minutes before proceeding to avoid accidentally cooking the eggs.
Mix in the eggs, 1 at a time, fully incorporating each egg before adding the next. Then add the vanilla.
Line a baking sheet with parchment paper.
Transfer the dough to a piping bag fitted with a closed star tip.
Pipe 18 1½-inch (3 cm) spiral rounds onto the baking sheet. Top each with a milk chocolate truffle. Pipe the dough in a spiral to cover the truffles, being careful to completely seal the chocolate. Immediately transfer the tray to the freezer and freeze for 1 hour, until solid.
Heat the oil in a deep pot until it reaches 350˚F (180˚C).
Fry in batches of 4 until nicely browned, about 3 minutes, turning so they fry evenly. Drain on a cooling rack, or paper towel-lined plate and dab off any excess oil.
Combine the remaining ½ cup sugar (100 G) and the cinnamon in a small bowl. Roll the warm churro bombs in the mixture to coat.