Preheat the oven to 180°C and lightly spray a doughnut pan with cooking oil.
In a small bowl, add the dairy-free milk and vinegar and mix. Set aside. In a medium size bowl add flour, baking powder, spices and salt and mix gently with a whisk to combine. In a large bowl, whisk together brown sugar, melted coconut oil and vanilla.
Add the milk mixture to the sugar and coconut oil and whisk to combine. Slowly add in the dry ingredients bit by bit, whisking in between each addition until the batter is smooth.
Pour batter into a large piping bag or ziplock bag and cut off the tip. Pipe the batter into the doughnut pan ensuring each hole is only half full.
Place in the oven and bake for 8 minutes or until the tops spring back when lightly touched. Let cool in the pan for 2 minutes and turn out onto a wire rack to cool completely.
Make the glaze. Mix together the coconut oil, vanilla and 1 tablespoon of dairy-free milk. Add in the icing sugar, a little at a time whisking completely between each addition. Add in more milk if needed to thin the glaze. You want the glaze to be thick but still runny enough to coat the doughnuts.
Dunk the top of each doughnut into the glaze and then place on a wire rack with a piece of baking paper under it to collect any excess glaze that drips off and set aside until the glaze has set.
Make the buttercream. In the bowl of a stand mixer (or using an electric hand mixer) beat together the dairy-free butter, icing sugar, vanilla. Add in the dairy-free milk a little at a time until the frosting is smooth and creamy. Add in a few drops of green gel food colouring and mix through until the desired colour is reached.
Decorate the doughnuts. Once the glaze has set, add the buttercream to a piping bag with a star tip attached (I used the Wilton 2D) and pipe the buttercream around the doughnuts to resemble a wreath. Decorate with sprinkles if desired.