2 tbsp flour = approximately 5 syns - which works out as less than a syn per slice if divided into 8 slices (or more).
1 tbsp Sukrin Gold is free. The cheesecake contains 6 1/2 tbsp (80g) which divided by 8 (or more) should be under your free allowance.
Please note I am not affiliated in any way with Slimming World. Syn values are based on the Slimming World online calculator. Nutritional information is always approximate, and will depend on the ingredients you choose, how you slice your dessert etc.