Preheat your oven to 180°C/350°F/Gas 6 and line a baking tray with parchment paper.
In a large bowl, mix together the flour and bicarbonate of soda and then rub in the butter until the mixture forms a breadcrumb like consistency.
Tip in the syrup, sugar and egg yolk and mix well until a dough is formed.
Gently shape into a ball and wrap in clingfilm, pop in the fridge and leave to chill for half an hour.
Once chilled, lightly flour your work station and roll out the dough until about 2cm in thickness.
Using an egg shaped cookie cutter, cut aprox 12 egg shapes and place on the baking tray.
Place in the oven to bake for 10 to 12 minutes until golden brown in colour.
Remove from the oven and leave to cool on the baking tray before transferring to the oven to cool completely.
Next make the icing: Place the icing in a large bowl and gradually add the water, beating for 10 minutes until the icing is glossy and smooth. If needed add a tablespoon extra of water.
Divide the icing into separate bowls and add different food colourings to each bowls (pink, yellow, green etc), keeping one plain if white icing is desired.
Fill icing bags with each colour and decorate as desired.
For tiny dots or squiggles. Use a cocktail stick.
Allow to dry for a few hours or overnight.