Gently heat the sugar, syrup, spices, and orange juice in a pan over a hob, do not boil but make sure the sugar is dissolved and nice and hot.
Once all melted together, add your diced Stork and stir until melted. Add the bicarbonate of soda and whist until foamy. Pop into a mixing bowl, ideally a stand mixer such as a Kitchen Aid and once cooled slightly tip in the flour. Mix slowly until the dough comes together and wrap and chill for at least an hour before rolling out. You can do this in advance if you wish, it will keep for a week in the fridge or you can also freeze.
When ready, knead well until pliable and roll out to approximately 4mm thickness. You can use guide sticks if you have them to make sure they are all an even thickness. Dust with a little more plain flour if you find it sticky. Cut out with a fluted round pastry cutter and place on a parchment lined baking tray.
Bake on 180 for approximately 10-12 minutes. If you want to cut out a shape in the biscuit, do this when half cooked with a small cutter of your choice. When cooked the dough should be firm to the touch and spring back when pressed lightly.
Leave to cool on a wire rack, and make your cinnamon buttercream.
Beat the Stork and sugar together with the vanilla seeds and cinnamon all at once, until very pale fluffy and creamy. Add the extract and beat again. If you find it stiff add a few tea spoons of boiled water warm and beat on fast.
Smooth the filling on one of the biscuit halves, use a piping bag if you find it easier but a dollop on a teaspoon will do, and then press the top biscuit onto the cinnamon cream filling to finish.