Place fennel seeds into a dry frying pan and toast on a medium high heat until hot and fragrant.
Place toasted seeds into the Thermomix bowl. Add garlic, mustard, orange juice, salt and EVOO and blend 10 sec/speed 6.
Add hazelnuts and blend 3 sec/speed 5. Remove from bowl and set aside.
Place ½ the spinach into Varoma dish. Pour water into Thermomix bowl and set Varoma into position. Cook 5 min/Varoma/speed 4. Add remaining spinach and cook 5 min/Varoma/speed 4. Stir through any extra spinach that will now fit in the Varoma dish and allow it to wilt with residual heat.
Toss dressing through and serve warm. Garnish with a few additional chopped hazelnuts.