Preheat the oven to 350°F (180°C).
Add the vegan butter and sugar to the bowl of your stand mixer and cream them together until smooth. Add vanilla extract and mix it in.
Sift the flour and cocoa into a mixing bowl and add baking soda and salt. Mix together.
Add dry ingredients to the wet and mix in with a spoon until crumbly. Add soy milk (or other non dairy milk) 1 Tbsp at a time until it forms a big ball of cookie dough that will stick together if you roll some of it into a ball. You may not need all 5 Tbsp of soy milk, this will entirely depend on the brand of vegan butter that you use.
Dust a baking mat with cocoa powder and transfer the ball of cookie dough onto the mat. Roll out with a rolling pin to around ¼ inch thick and cut out your cookies. If you just want round cookies, you can skip this step and just roll them into balls, using the bottom of a glass dipped in cocoa powder to press down on them to flatten into neat round shapes.
Place the cut out cookies onto a parchment lined baking tray.
Bake in the oven for 10 minutes.
Allow the cookies to cool completely before frosting.
Add all frosting ingredients except for the red food coloring into the bowl of your stand mixer and starting at slow speed gradually increase speed until perfectly smooth. Your frosting should be quite thick, yet still spreadable. If it's too thick add a drop or two more soy milk, if it's too thin, add some more powdered sugar.
Separate the frosting into two bowls. Add a drop of red food coloring to the one bowl and mix it in, which will create a pink color. Add a few more drops to the second bowl creating a darker pink or red.
Spread the frosting on the cookies and then top with vegan sprinkles or other decorations.