Method (cookie)

1. Preheat oven to 180 degrees C fan. Line a 10 inch round loose base / spring form cake tin with grease proof paper. 
2. Mix the ground flaxseed and water together in a small bowl, then set aside for 5 minutes to thicken. 
3. In a mixing bowl, add in the butter / margarine, sugar and vanilla. Mix until smooth and creamy. You can mix this in a stand mixer with paddel attachment or a bowl with a wooden spoon.
4. Add the thickened flax egg and mix until smooth.
5. Add sift in the flour, cornstarch / cornflour and bicarbonate of soda. Mix until combined – the dough will be sticky.
6. In in the chocolate chips and mix until evenly distributed. 
7. Add dough to prepared pan and evenly spread out with a off set spatula – add a few remaining chocolate chips to the top and gently press down.
8. Bake for 20-25 minutes, or until lightly browned on top, and a toothpick inserted into the middle of the cookie cake comes out clean without any wet dough on it.
9. Remove from the oven and allow to cool completely, then remove from the tin and place on a serving plate ready for decorating.  

Method (frosting)

1. In a large mixing bowl, add in the dairy-free butter and whip until creamy. I use a stand mixer with a balloon whisk attachment, a hand mixer will work great too.
2. Sift in the icing sugar and vanilla extract, whip for 5 minutes until creamy and pale in colour. If it’s too stiff / thick, add in a few more chunks of butter. Too soft, add in more icing sugar.

Decoration

1. Depending on your designs and colour choices, separate the buttercream into separate bowls and colour with your chosen food gels. Use cocoa powder for any chocolate buttercream.
2. Transfer all the buttercream into separate piping bags with either the tip snipped off or with your chosen piping nozzles.
3. Decorate the cookie slices as you fancy. For the gravestone cookie, once you have piped on your chosen buttercream, blitz up some Oreo cookies, pour the crumbs on to a plate and press the buttercream into the Oreos. It will stick, then flip back and decorate as you like. I made the pumpkins with orange buttercream and green for the stalk, ghosts and mummies in white with black eyes, bats with black buttercream and an Oreo bat on top (Oreo bat recipe here). To make the spider, I melted dairy-free dark chocolate, added it into a piping bag, piped a spider shape onto grease proof paper and popped it into the freezer to set. I stuck on some googley eyes with melted chocolate. Super simple but effective.