In a medium bowl combine gluten free flour, cinnamon and salt. Make a hole in the middle and place the yeast, being careful it doesn't touch the salt. Add the eggs (save a half an yolk for the top), the milk and the maple syrup and start kneading. Then toss the butter little by little while continuing to knead for 7-8 minutes. Cover the bowl with a cling film and allow it to rest in a warm spot until doubled in size.
While the dough is resting, in a small bowl place 2 tbsp corn starch and pour in a small amount of the milk. Gently stir to form a slurry. Heat the rest of the milk along with vanilla, maple syrup and salt. When it comes to boil remove from the heat.
Beat 2 egg yolks in a bowl. Add the corn starch slurry and mix well. Then gradually pour the hot milk and continue stirring until there are no lumps and the mixture is smooth. Pour it in a saucepan and cook on a very low heat. Stir constantly with a wooden spoon, until thickens (around 10 minutes). Then leave the custard to cool down.
Preheat the oven to 180°C ~ 356°F. Then grease and line a baking tin. I used a medium round disposable tin.
Roll the dough out on some flour and form a rectangle sheet (12x15 inches). Spread the cold vanilla custard on it. Roll it gently, then cut slices 1.5 inches thick. Arrange these slices in a round greased baking tin and leave to swell from half an hour to up to an hour at room temperature.
Mix the half yolk with 1 tbsp water and brush the top of the brioche until is all utilised. Bake for 35-40 minutes or until golden and puffed. Serve hot or cold with black cherry jam (or jam of your choice) or on its own.
Enjoy!