Line the bottom of a 20cm loose bottom or springform cake tin with baking paper.
Slice hot cross buns in half width ways and place the bottom halves of the buns along the bottom of the cake tin. Use any spare spread to fill in the gaps.
For the custard filling, add the soy milk, cornflour, maple syrup and vanilla to a medium saucepan over high heat. Mix with a spoon until thickened (it should be the thickness of yoghurt). Make sure there are no lumps.
Pour custard on top of hot cross buns and scatter blueberries on top. Arrange the remaining halves of hot cross bun onto the custard and set aside in the fridge.
When the custard is set or dry to the touch, remove the cake from the tin, slice and enjoy! To store, keep in an airtight container for up to 5 days.