Wash hands with soap and water. Ensure worksurface is clean.
In an electric blender, blend 1 cup (25 g) of the Splenda® with 3 tablespoons of cornstarch until very finely powdered.
Empty into a bowl.
Repeat process until all is mixed (yes, at the final step there will only be 2 tbsp cornstarch).
Stir gently to mix all the batches into each other.
Store in a tightly sealed jar or container.
Blend 1 to 2 cups (25 to 50 g) of Splenda® at a time for best results. This is the reason for not just whacking it all at once into the blender jug, though you are welcome to try that the first time out if you wish and see if you get results you are happy with.The mix recipe is easily doubled or tripled, but still it's best to blend only a cup or two at a time.