3 syns for a Tall Starbucks Hazelnut Hot Chocolate!
This isn't official, but is what I figured out, so if you want to stick to official numbers, ignore this. But it makes sense.
Officially, it's 11 syns for a tall hot chocolate with skimmed milk, with the whipped cream. Minus 3 syns for the whipped cream. Use the skimmed milk as your Healthy Extra A, and that saves 5 syns (the Starbucks tall cups hold a tiny bit more than your permitted allowance of skimmed milk, so I've knocked half a syn off the saving just to be safe). Sugar free syrups are syn free, so using sugar free hazelnut syrup, there you have it; a 3 syn hazelnut hot chocolate!
If you'd like to be safe, you could call it a 4 syn hot chocolate. But typing the calories on the Snackulator of just the hot chocolate syrup used also brings up 3 syns.