Preheat your oven to 180°C/350°F (160°C/325°F if using a fan or convection oven). Line a baking sheet with baking paper.

In a large bowl, mix together the vegan margarine and sugar until combined. Add the vanilla and mix again.

Add in the flour, baking soda and soy milk. Mix everything together with your spoon and when it starts to stick, use your hands to form a dough. It may feel a bit crumbly at this point but don't worry as it will hold together once chilled.

Wrap the dough in cling film or tinfoil and place it in the fridge for 30 minutes.

Once chilled, unwrap the dough and use your hands to soften it slightly.

Roll it out on a floured surface until it's around ¼ of an inch thick. Dip your cookie cutter in flour to prevent sticking and cut out your shapes.

Transfer them to your baking sheet and bake for 10-15 minutes. Large cookies may take a few minutes longer. You'll know they're ready when they feel firm at the edges and have tiny cracks all over them. Don't let them brown otherwise they will be too crunchy.

Let them cool completely on the tray.

Prepare the icing by mixing the icing sugar and water together in a bowl. Add more water or icing sugar as required (see notes). If using royal icing, follow the instructions on that post.

Divide the icing up into bowls and add your desired colour to each bowl. Transfer into piping bags and decorate the cookies. Let each layer of icing set before adding the next.