Mix the Dry Ingredients. In a medium bowl, sift together the powdered sugar, cocoa powder, and salt until smooth and lump-free.

Add the Wet Ingredients. Stir in the vanilla extract and corn syrup. Add water one drop at a time, mixing until a thick, smooth paste forms.

You’re looking for a consistency similar to thick frosting—firm enough to hold its shape, but soft enough to pipe easily. It should look like very thick frosting or a dense cookie dough. If it's crumbly and won't come together, add water a few drops at a time. If it's too loose and drips off the spoon, add powdered sugar a tablespoon at a time.

Pipe the Sprinkles. Fit a piping bag with a small round tip, size 2 or 3 works perfectly. If you don't have piping tips, you can use a zip-top bag and snip a very small corner off, but a proper tip gives you much cleaner results. Scoop the dough into the bag, press out any air pockets, and twist the top to seal.

Pipe thin lines onto parchment. Line a baking sheet with parchment paper. Hold the piping bag at a 45-degree angle and pipe continuous straight lines across the sheet, each about four to five inches long. Space them about half an inch apart so they don't stick together as they dry. The lines should be thin, about the width of a standard sprinkle, roughly an eighth of an inch in diameter. If they're too thick, they'll take forever to dry and won't have that satisfying crunch.

Let Them Dry. Allow the lines to dry at room temperature for 4–6 hours or overnight until firm.

Cut into Sprinkles. Once fully set, use a knife or kitchen scissors to cut into small sprinkle pieces.